Method and apparatus for providing variable rate data in a communications system using non-orthogonal overflow channels

• US 7,167,460 B2
• Filed: 05/08/2001
• Issued: 01/23/2007
• Est. Priority Date: 02/28/1995
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Miller, David S., Zehavi, Ephraim, LaRocca, Judith
• Primary Examiner(s): Shah; Chirag
• Assistant Examiner(s): Nguyen; PhuongChau Ba
• Application Number:
  US09/851,655
• Publication Number:
  US 20010024432A1
• Time in Patent Office: 2,086 Days
• Field of Search: 370/320, 370/335, 370/342, 370/441, 370/442, 370/468, 375/130, 375/136, 375/137, 375/141
• US Class Current: 370/335
• CPC Class Codes: H04B 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

A variable rate transmission system where a packet of variable rate data is transmitted on a traffic channel if the capacity of the traffic channel is greater than or equal to the data rate of the packet. When the rate of the packet of variable rate data exceeds the capacity of the traffic channel, the packet is transmitted on a traffic channel and at least one overflow channel. Also described is a receiving system for receiving and reassembling the data transmitted on the traffic channel and at least one additional overflow channel.

Claims

1. In code division multiple access (CDMA) communication system, wherein packets of data are transmitted using a plurality of orthogonal code sequences and wherein each user of said code division multiple is allocated an orthogonal code sequence for communication on a traffic channel for transmitting variable rate packets of data symbols, an apparatus comprising:

a channel packetizer configured to receive said variable rate packets and, when a number of said data symbols included in ones of said variable rate packets exceeds a threshold value to split each of said ones of said variable rate packets into a traffic packet and at least one overflow packet;

a first modulator configured to receive said traffic packet and to modulate said traffic packet in accordance with said orthogonal code sequence of said plurality of orthogonal code sequences and to modulate said orthogonal modulated traffic packet in accordance with a first pseudorandom noise (PN) sequence;

a second modulator configured to receive said at least one overflow packet and to modulate said at least one overflow packet in accordance with an orthogonal code sequence of said plurality of orthogonal code sequences and to modulate said at least one orthogonal modulated overflow packet in accordance with at least one additional pseudorandom noise (PN) sequence wherein said at least one additional PN sequence is nonorthogonal to said first PN sequence; and

a transmitter configured to transmit said traffic packet on said traffic channel and to transmit at least one overflow packet on said at least one overflow channel.

2. The apparatus of claim 1 wherein said channel packetizer is responsive to a rate signal.

3. The apparatus of claim 1 further comprising a variable rate vocoder configured to receive speech samples and to compress said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

4. The apparatus of claim 3 further comprising an encoder configured to error correction code said variable rate packets.

5. The apparatus of claim 4 further comprising an interleaver configured to reorder said variable rate packets, said encoder being disposed between said variable rate vocoder and said interleaver.

6. An apparatus for transmitting variable rate packets of data symbols comprising;

means for receiving said variable rate packets and for dividing each of said variable rate packets including more than a threshold number of said data symbols into a traffic packet and into an overflow packet, each said traffic packet being provided to a first packetizer output and each said overflow packet being provided to a second packetizer output;

means for receiving said traffic packet and for modulating said traffic packet in accordance with an orthogonal code sequence of a plurality of orthogonal code sequences and having a first output for providing said orthogonal code sequence modulated traffic packet;

means for receiving said orthogonal code modulated traffic packet and for modulating said orthogonal code modulated traffic packet in accordance with a first PN sequence;

means for receiving said overflow packet and for modulating said overflow in accordance with a second orthogonal code sequence of said plurality of orthogonal code sequences and having a second output for providing said orthogonal code modulated overflow packet;

means for receiving said orthogonal code modulated overflow packet and for modulating said orthogonal code modulated overflow packet in accordance with a second PN sequence which is non-orthogonal to said first PN sequence; and

a transmitter means having a first input coupled to said first modulator output and having a second input coupled to said second modulator output, said transmitter further having an output.

7. The apparatus of claim 6 wherein said channel packetizer is responsive to a rate signal.

8. The apparatus of claim 7 further comprising a variable rate vocoder for receiving speech samples and for compressing said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

9. The apparatus of claim 8 further comprising an encoder for error correction coding said variable rate packets.

10. The apparatus of claim 9 further comprising an interleaver for reordering said variable rate packets, said encoder being disposed between said variable rate vocoder and said interleaver.

11. An apparatus for transmitting variable rate packets of data symbols comprising;

a channel packetizer having an input for receiving said variable rate packets and for dividing each of said variable rate packets including more than a threshold number of said data symbols into a traffic packet and into an overflow packet, each said traffic packet being provided to a first packetizer output and each said overflow packet being provided to a second packetizer output;

a first modulator having an input for receiving said traffic packet and for modulating said traffic packet in accordance with an orthogonal code sequence of a plurality of orthogonal code sequences and having a first output for providing said orthogonal code sequence modulated traffic packet;

a first PN modulator having an input for receiving said orthogonal code modulated traffic packet and for modulating said orthogonal code modulated traffic packet in accordance with a first PN sequence;

a second modulator having an input for receiving said second packet and for modulating said traffic packet in accordance with a second orthogonal code sequence of said plurality of orthogonal code sequences and having a second output for providing said orthogonal code modulated traffic packet;

a second PN modulator having an input for receiving said orthogonal code modulated overflow packet and for modulating said orthogonal code modulated overflow packet in accordance with a second PN sequence which is non-orthogonal to said first PN sequence; and

a transmitter having a first input coupled to said first modulator output and having a second input coupled to said second modulator output, said transmitter further having an output.

12. The apparatus of claim 11 wherein the first PN modulator and the second PN modulator is responsive to a rate signal.

13. The apparatus of claim 11 further comprising a receiver for receiving speech samples and a compressor for compressing said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

14. The apparatus of claim 13 further comprising an error correction coder for coding said variable rate packets.

15. The apparatus of claim 11 further comprising an interleaver for interleaving said variable rate packets.

16. An apparatus for transmitting variable rate packets of data symbols comprising:

a channel packetizer having an input for receiving said variable rate packets and for dividing each of said variable rate packets including more than a threshold number of said data symbols into a traffic packet and into an overflow packet, each said traffic packet being provided to a first packetizer output and each said overflow packet being provided to a second packetizer output, said channel packetizer responsive to a rate signal;

a first modulator having an input for receiving said traffic packet and for modulating said traffic packet in accordance with an orthogonal code sequence of a plurality of orthogonal code sequences and having a first output for providing said orthogonal code sequence modulated traffic packet;

a first PN modulator having an input for receiving said orthogonal code modulated traffic packet and for modulating said orthogonal code modulated traffic packet in accordance with a first PN sequence;

a second modulator having an input for receiving said overflow packet and for modulating said overflow packet in accordance with a second orthogonal code sequence of said plurality of orthogonal code sequences and having a second output for providing said orthogonal code modulated overflow packet;

a second PN modulator having an input for receiving said orthogonal code modulated overflow packet and for modulating said orthogonal code modulated overflow packet in accordance with a second PN sequence which is non-orthogonal to said first PN sequence; and

a transmitter having a first input coupled to said first modulator output and having a second input coupled to said second modulator output, said transmitter further having an output.

17. The apparatus of claim 16 further comprising a variable rate vocoder for receiving speech samples and for compressing said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

18. The apparatus of claim 17 further comprising an encoder for error correction coding said variable rate packets.

19. The apparatus of claim 18 further comprising an interleaver for reordering said variable rate packets, said encoder being disposed between said variable rate vocoder and said interleaver.

20. In a system in which variable rate packets of data symbols including in excess of a threshold number of said data symbols are each transmitted as a traffic packet and an overflow packet, an apparatus for receiving said variable rate packets of data symbols comprising:

a traffic demodulator configured to demodulate said traffic packet received by said apparatus using a first pseudonoise (PN) sequence and a sequence of a first set of orthogonal sequences to provide a demodulated traffic packet;

an overflow demodulator configured to demodulate said overflow packet received by said apparatus using a second pseudonoise (PN) sequence and a second sequence of said first set of orthogonal sequences to provide a demodulated overflow packet;

said overflow demodulator dynamically allocated based on whether said variable rate packets of data symbols exceed a threshold number of said data symbols, wherein said first PN sequence is temporally offset and non-orthogonal to said second PN sequence; and

a combiner configured to combine said demodulated traffic packet and said demodulated overflow packet to provide said variable rate packets.

21. The apparatus of claim 20, wherein said traffic demodulator further comprises:

an orthogonal traffic sequence generator configured to generate a traffic sequence; and

an orthogonal traffic despreader configured to receive said demodulated traffic packet and to despread said demodulated traffic packet using said traffic sequence,

wherein said overflow demodulator further comprises;

an orthogonal overflow sequence generator configured generate an overflow sequence; and

an orthogonal overflow despreader configured to receive said demodulated overflow packet and to despread said demodulated overflow packet using said overflow sequence.

22. The apparatus of claim 20, wherein said combiner continuously monitoring said traffic demodulator and said overflow demodulator.

23. The apparatus of claim 20, wherein said combiner monitors said overflow demodulator only when instructed by said traffic demodulator.

24. An apparatus for transmitting variable rate packets of data symbols comprising:

a channel packetizer configured to receive said variable rate packets and, when a number of said data symbols included in ones of said variable rate rackets exceeds a threshold value to split each of said ones of said variable rate packets into a traffic packet and at least one overflow packet;

a first modulator configured to receive said traffic packet and to modulate said traffic packet in accordance with a first code sequence; and

a second modulator configured to receive said at least one overflow packet and to modulate said at least one overflow packet in accordance with a second code sequence that is orthogonal to the first code sequences if usage of orthogonal code sequences is low, and otherwise to modulate said at least one overflow packet in accordance with a code sequence that is not orthogonal to the first code sequences;

wherein the first modulator is further configured to modulate said code sequence modulated traffic packet in accordance with a first pseudorandom noise (PN) sequence; and

wherein the second modulator is further configured to modulate said at least one code sequence modulated overflowed packet in accordance with at least one additional PN sequence wherein said at least one additional PN sequence is nonorthogonal to said first PN sequence.

25. The apparatus of claim 24, further comprising:

a transmitter configured to transmit said traffic packet on a traffic channel and to transmit at least one overflow packet on at least one overflow channel.

26. The apparatus of claim 24 further comprising a variable rate vocoder configured to receive speech samples and to compress said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

27. The apparatus of claim 26 further comprising an encoder configured to error correction code said variable rate packets.

28. The apparatus of claim 27 further comprising an interleaver configured to reorder said variable rate packets, said encoder being disposed between said variable rate vocoder and said interleaver.

29. A method for transmitting variable rate packets of data symbols comprising:

receiving said variable rate packets;

splitting ones of said variable rate packets into a traffic packet and at least one overflow packet when a number of said data symbols included in ones of said variable rate packets exceeds a threshold value;

modulating said traffic packet in accordance with a first code sequence; and

modulating said at least one overflow packet in accordance with a second code sequence that is orthogonal to the first code sequence if usage of orthogonal code sequences is low, and otherwise modulating said at least one overflow packet in accordance with a second code sequence that is not orthogonal to the first code sequence, modulating said code sequence modulated traffic packet in accordance with a first pseudorandom noise (PN) sequence;

modulating said at least one code sequence modulated overflow packet in accordance with at least one additional PN sequence wherein said at least one additional PN sequence is non-orthogonal to said first PN sequence; and

transmitting said traffic packet on a traffic channel and transmitting at least one overflow packet on at least one overflow channel.

30. The method of claim 29 further comprising:

receiving speech samples; and

compressing said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

31. The method of claim 29 further comprising error correction coding said variable rate packets.

32. An apparatus for transmitting variable rate packets of data symbols comprising:

means for receiving said variable rate packets;

means for splitting ones of said variable rate packets into a traffic packet and at least one overflow packet when a number of said data symbols included in ones of said variable rate packets exceeds a threshold value;

means for modulating said traffic packet in accordance with a first code sequence; and

means for modulating said at least one overflow packet in accordance with a second code sequence that is orthogonal to the first code sequence if usage of orthogonal code sequences is low, and otherwise for modulating said at least one overflow packet in accordance with a second code sequence that is not orthogonal to the first code sequence means for modulating said code sequence modulated traffic packet in accordance with a first pseudorandom noise (PN) sequence;

means for modulating said at least one code sequence modulated overflow packet in accordance with at least one additional PN sequence wherein said at least one additional PN sequence is non-orthogonal to said first PN sequence; and

means for transmitting said traffic packet on a traffic channel and for transmitting at least one overflow packet on at least one overflow channel.

33. The apparatus of claim 32 further comprising:

means for receiving speech samples; and

means for compressing said speech samples in accordance with a variable rate vocoder format to provide said variable rate packets.

34. The apparatus of claim 32 further comprising means for error correction coding said variable rate packets.

35. An apparatus for receiving variable rate packets of data symbols transmitted as a traffic packet and an overflow packet, comprising:

a traffic demodulator configured to demodulate said traffic packet using a first code sequence; and

an overflow demodulator configured to demodulate said overflow packet using a second code sequence that is orthogonal to the first code sequence if usage of orthogonal code sequences is low, and otherwise to modulate said overflow packet using a second code sequence that is not orthogonal to the first code sequence;

wherein said traffic demodulator is further configured to demodulated said traffic packet using a first pseudonoise (PN) sequence to provide a demodulated traffic packet; and

wherein said overflow demodulator is further configured to demodulated said overflow packet using a second pseudo-noise (PN) sequence to provide a demodulated overflow packet;

wherein said first PN sequence is temporally offset and non-orthogonal to said second PN sequence.

36. The apparatus of claim 35 further comprising:

a combiner configured to combine said demodulated traffic packet and said demodulated overflow packet to provide said variable rate packets.

37. The apparatus of claim 35 wherein said overflow demodulator is dynamically allocated based on whether said variable rate packets of data symbols exceed a threshold number of said data symbols.

38. A method for receiving variable rate packets of data symbols transmitted as a traffic packet and an overflow packet, comprising:

demodulating said traffic packet using a first code sequence; and

demodulating said overflow packet using a second code sequences that is orthogonal to the first code sequence if usage of orthogonal code sequences is low, and otherwise to modulating said overflow packet using a second code sequence that is not orthogonal to the first code sequence;

demodulating said traffic packet using a first pseudo-noise (PN) sequence to provide a demodulated traffic packet;

demodulating said overflowed packet using a second pseudo-noise (PN) sequence to provide a demodulated overflow packet;

wherein said first PN sequence is temporally offset and nonorthogonal to said second PN sequence; and

combining said demodulating said demodulated traffic packet and said demodulated overflowed packet to provide said variable rate packets.

39. An apparatus for receiving variable rate packets of data symbols transmitted as a traffic packet and an overflow packet, comprising:

means for demodulating said traffic packet using a first code sequence; and

means for demodulating said overflow packet using a second code sequence that is orthogonal to the first code sequence if usage of orthogonal code sequences is low, and otherwise for modulating said overflow packet using a second code sequence that is not orthogonal to the first code sequence;

means for demodulating said traffic packet using first pseudo-noise (PN) sequence to provide a demodulated traffic packet;

means for demodulating said overflow packet;

wherein said first PN sequence is temporally offset and non-orthogonal to said second PN sequence; and

means for combining said demodulated traffic packet and said demodulated overflow packet to provide said variable rate packets.