Method for providing and selecting amongst multiple data rates in a time division multiplexed system

• US 5,533,004 A
• Filed: 11/07/1994
• Issued: 07/02/1996
• Est. Priority Date: 11/07/1994
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Crisler, Kenneth J., Jasper, Steven C.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Jung, Min
• Application Number:
  US08/334,982
• Time in Patent Office: 603 Days
• Field of Search: 370/11, 370/95.3, 370/84, 370/79, 375/261, 375/262, 375/265, 375/298, 375/341, 375/225, 371/43
• US Class Current: 370/204
• CPC Class Codes: H04B 7/2659 for data rate control
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

In a Radio Frequency (RF) communication system using Time Division Multiple Access (TDMA) having time slots of a common duration, a quantity of information bits to be transmitted is provided. Based at least in part on the number of information bits to be transmitted, a modulation technique is selected from a plurality of modulation techniques. Based at least in part on the modulation technique selected and the common duration of the time slots, the information bits are formatted into blocks, each block containing an equal number of information bits. The blocks are transmitted in the time slots such that a predetermined symbol rate is maintained.

Claims

1. A method comprising the steps of:

providing a communication channel having a plurality of time slots, wherein each of the plurality of time slots has a common duration;

providing a quantity of information bits to be transmitted to at least one intended recipient;

providing a plurality of modulation techniques having corresponding effective data transmission rates;

selecting one of the plurality of modulation techniques to produce a selected modulation technique;

regardless of which of the plurality of modulation techniques was selected;

formatting the information bits into at least one block, such that an identical number of information bits are always contained within a single block;

transmitting the at least one block in at least one of the time slots at a predetermined constant symbol rate using the selected modulation technique.

2. The method of claim 1, wherein the step of transmitting the at least one block in at least one of the time slots includes the step of transmitting the at least one block such that all of the time slots will only contain an integer number of the blocks.

3. The method of claim 1, wherein the step of providing a communication channel includes the step of providing a communication channel that is one of a plurality of communication channels, wherein the plurality of communication channels are offset from adjacent communication channels by 25 kHz.

4. The method of claim 3, wherein the step of providing a communication channel having a plurality of time slots includes the step of providing a communication channel having a plurality of time slots, wherein each time slot has a duration of 15 milliseconds.

5. The method of claim 1, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 64 quadrature amplitude modulation technique.

6. The method of claim 5, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 16 quadrature amplitude modulation technique.

7. The method of claim 6, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein:

one of the plurality of modulation techniques comprises a 256 quadrature amplitude modulation technique; and

one of the plurality of modulation techniques comprises a quadrature phase shift keying modulation technique.

8. The method of claim 1, wherein the step of selecting one of the plurality of modulation techniques includes the step of selecting a predetermined one of the plurality of modulation techniques as an initial default selection.

9. The method of claim 1, wherein the step of selecting one of the plurality of modulation techniques includes the step of selecting one of the plurality of modulation techniques at least as a function of the quantity of information bits.

10. The method of claim 9, wherein the step of selecting one of the plurality of modulation techniques at least as a function of the quantity of information bits includes the step of using a first modulation technique when the quantity of information bits are greater in number than a predetermined quantity.

11. The method of claim 10, wherein the step of selecting one of the plurality of modulation techniques at least as a function of the quantity of information bits includes the step of using a second modulation technique when the quantity of information bits are lesser in number than a predetermined quantity, wherein the second modulation technique has a lower effective data rate than the first modulation technique.

12. The method of claim 1, wherein the step of selecting one of the plurality of modulation techniques includes the step of selecting one of the plurality of modulation techniques as a function of the at least one intended recipient.

13. The method of claim 12, wherein the step of selecting one of the plurality of modulation .techniques as a function of the at least one intended recipient includes the step of selecting a first modulation technique when there is only one intended recipient.

14. The method of claim 13, wherein the step of selecting one of the plurality of modulation techniques as a function of the at least one intended recipient includes the step of selecting a second modulation technique when there is more than one intended recipient, where the second modulation technique has a lower effective data rate than the first modulation technique.

15. The method of claim 1, wherein the step of formatting the information bits into at least one block includes the step of formatting the information bits into at least one block, wherein the information bits include both user data and cyclic redundancy check error detection coding.

16. The method of claim 1, wherein the step of formatting the information bits into at least one block includes the step of formatting the information bits into at least one block, wherein the information bits include both user data and error detection coding.

17. The method of claim 16, wherein the step of formatting the information bits into at least one block, such that an identical number of information bits are always contained within a single block includes the step of formatting the information bits into at least one block, such that 165 information bits are always contained within a single block.

18. The method of claim 17, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 64 quadrature amplitude modulation technique, wherein:

the 64 quadrature amplitude modulation technique includes an effective trellis coding rate 2/3rds;

the 64 quadrature amplitude modulation technique includes error correction coding; and

the 64 quadrature amplitude modulation technique has an effective 4 to 1 information-bit-to-transmitted-symbol ratio.

19. The method of claim 18, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 16 quadrature amplitude modulation technique, wherein:

the 16 quadrature amplitude modulation technique includes an effective trellis coding rate 1/2;

the 16 quadrature amplitude modulation technique includes error correction coding; and

the 16 quadrature amplitude modulation technique has an effective 2 to 1 information-bit-to-transmitted-symbol ratio.

20. The method of claim 19, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein the plurality of modulation techniques further comprise:

a 256 quadrature amplitude modulation technique, wherein;

the 256 quadrature amplitude modulation technique includes an effective trellis coding rate 3/4ths;

the 256 quadrature amplitude modulation technique includes error correction coding; and

the 256 quadrature amplitude modulation technique has an effective 6 to 1 information-bit-to-transmitted-symbol ratio;

a quadrature phase shift keyed modulation technique, wherein;

the quadrature phase shift keyed modulation technique includes an effective trellis coding rate 1/2;

the quadrature phase shift keyed modulation technique includes error correction coding; and

the quadrature phase shift keyed modulation technique has an effective 1 to 1 information-bit-to-transmitted-symbol ratio.

21. A method for transmitting user data through a wireless communication medium using at least one of a plurality of modulation techniques having corresponding effective data transmission rates, comprising the steps of:

providing a communication channel having a plurality of time slots, wherein each of the plurality of time slots has a 15 millisecond duration;

providing a quantity of information bits to be transmitted to at least one intended recipient, wherein the information bits include both user data and error detection coding bits;

providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 64 quadrature amplitude modulation technique, wherein;

the 64 quadrature amplitude modulation technique includes an effective trellis coding rate 2/3rds;

the 64 quadrature amplitude modulation technique includes error correction coding; and

the 64 quadrature amplitude modulation technique has an effective 4 to 1 information-bit-to-transmitted-symbol ratio;

selecting one of the plurality of modulation techniques to produce a selected modulation technique;

regardless of which of the plurality of modulation techniques was selected;

formatting the information bits into at least one block, such that an identical number of information bits are always contained within a single block;

transmitting the at least one block in at least one of the time slots at a predetermined constant symbol rate using the selected modulation technique.

22. The method of claim 21, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein one of the plurality of modulation techniques comprises a 16 quadrature amplitude modulation technique, wherein:

the 16 quadrature amplitude modulation technique includes an effective trellis coding rate 1/2;

the 16 quadrature amplitude modulation technique includes error correction coding; and

the 16 quadrature amplitude modulation technique has an effective 2 to 1 information-bit-to-transmitted symbol ratio.

23. The method of claim 22, wherein the step of providing a plurality of modulation techniques includes the step of providing a plurality of modulation techniques, wherein the plurality of modulation techniques further comprise:

a 256 quadrature amplitude modulation technique, wherein;

the 256 quadrature amplitude modulation technique includes an effective trellis coding rate 3/4ths;

the 256 quadrature amplitude modulation technique includes error correction coding; and

the 256 quadrature amplitude modulation technique has an effective 6 to 1 information-bit-to-transmitted-symbol ratio;

a quadrature phase shift keyed modulation technique, wherein;

the quadrature phase shift keyed modulation technique includes an effective trellis coding rate 1/2;

the quadrature phase shift keyed modulation technique includes error correction coding; and

the quadrature phase shift keyed modulation technique has an effective 1 to 1 information-bit-to-transmitted-symbol ratio.