Preamble channel decoding

• US 7,230,941 B2
• Filed: 04/26/2001
• Issued: 06/12/2007
• Est. Priority Date: 04/26/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wei, Yongbin, Odenwalder, Joseph P., Sarkar, Sandip
• Primary Examiner(s): Vu; Huy D.
• Assistant Examiner(s): RYMAN, DANIEL J
• Application Number:
  US09/843,553
• Publication Number:
  US 20020159412A1
• Time in Patent Office: 2,238 Days
• Field of Search: 370/335, 370/342, 370/441, 370/468, 370/509
• US Class Current: 370/342
• CPC Class Codes: H04L 1/003 Adaptive formatting arrangements particular to signalling, e.g. variable amount of bits
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 25/0262 Arrangements for detecting the data rate of an incoming signal

Abstract

Rather than attaching a preamble to a data traffic subpacket, a preamble channel is transmitted along with a traffic channel. In a system wherein the data traffic subpackets are variably sized, preambles can also be variably sized if a target station can decode variably sized preambles. A method and apparatus for decoding variably sized preamble subpackets are presented herein.

Claims

1. An apparatus in a remote station for decoding a preamble channel, wherein the preamble channel carries variably sized preamble sequences, comprising:

a plurality of preamble size detection elements for determining a number of slots occupied by a preamble sequence on the preamble channel which is separate from a traffic channel, wherein each of the plurality of preamble size detection elements outputs a potential preamble sequence and a best path metric; and

a selection element for choosing a true preamble sequence from the potential preamble sequences output from the plurality of detection elements;

wherein each of the plurality of detection elements comprises;

a de-interleaver for operating over a predetermined number of slots of the preamble channel, wherein each de-interleaver of the plurality of detection elements operates over a different predetermined number of slots;

a decoder for extracting preamble information on from the preamble sequence; and

a sequence checker for determining if an identifier is present in the preamble information.

2. The apparatus of claim 1, wherein at least one of the plurality of detection elements further comprises a combining element operating over at least two slots, wherein the at least one of the plurality of detection elements operates over the at least two slots.

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

4. The apparatus of claim 1, wherein the identifier is a Medium Access Control (MAC) identifier.

5. The apparatus of claim 1, wherein each decoder in the plurality of detection elements outputs a best path metric value and the potential preamble sequence.

6. An apparatus in a remote station for decoding a preamble channel, wherein the preamble channel carries variably sized preambles sequences, comprising:

a plurality of preamble size detection elements for determining a number of slots occupied by preamble sequence on the preamble channel which is separate from a traffic channel, wherein each of the plurality of preamble size detection elements outputs a potential preamble sequence and a best path metric; and

a selection element for choosing a true preamble sequence from the potential preamble sequences output from the plurality of detection elements, wherein the selection element is further for determining the number of slots occupied by a data subpacket on a non-preamble channel, wherein the number of slots occupied by the data subpacket is associated with the number of slots occupied by the true preamble sequence.

7. A method for determining preamble information transmitted on a preamble channel, comprising:

de-interleaving over one slot of the preamble channel which is separate from a traffic channel to form a first de-interleaved sequence;

de-interleaving over at least two slots of the preamble channel to form a second de-interleaved sequence, wherein the first slot of the at least two slots is the slot used in the first de-interleaving step;

soft-combining the second de-interleaved sequence;

decoding the first de-interleaved sequence to generate a first potential preamble and a first metric value;

decoding the second de-interleaved sequence to generate a second potential preamble and a second metric value; and

choosing between the first potential preamble and the second potential preamble to select true preamble.

8. The method of claim 7, wherein choosing between he first potential preamble and the second potential preamble comprise:

checking for an identifier in the first potential preamble and in the second potential preamble; and

selecting either the first potential preamble or the second potential preamble in accordance with the presence of the identifier.

9. The method of claim 8, wherein selecting either the first potential preamble or the second potential preamble comprises selecting either the first potential preamble or the second potential preamble in accordance with the better of the first metric value or the second metric value if the identifier is present in both the first potential preamble and the second potential preamble.

10. The method of claim 8, wherein selecting either the first potential preamble or the second potential preamble comprises selecting either the first potential preamble or the second potential preamble in accordance with the better of the first metric value or the second metric value if the identifier is not present in the first potential preamble or in the second potential preamble.

11. A method for determining preamble information carried by a preamble channel which is separate from a traffic channel, comprising:

de-interleaving over a variable number of slots for a plurality of de-interleaving results;

soft-combining symbols within each of the plurality of de-interleaving results, except in the instance when the de-interleaving is over one slot;

decoding the one-slot de-interleaved symbol and the soft-combined symbol associated with each of the plurality of de-interleaving results;

checking the decoded symbols for an identifier; and

extracting the preamble information from the checked symbol that carries the identifier.

12. An apparatus for determining preamble information transmitted on a preamble channel, comprising:

means for de-interleaving over one slot of the preamble channel which is separated from a traffic channel to form a first de-interleaved sequence;

means for de-interleaving over at least two slots of the preamble channel to form a second de-interleaved sequence, wherein the first slot of the at least two slots is the same slot as the first de-interleaving step;

means for soft-combining the second de-interleaved sequence;

means for decoding the first de-interleaved sequence to generate a first potential preamble and a first metric value and for decoding the second de-interleaved sequence to generate a second potential preamble and a second metric value; and

means for choosing between the first potential preamble and the second potential preamble as a true preamble.

13. An apparatus for determining preamble information carried by a preamble channel which is separate from a traffic channel, comprising:

means for de-interleaving over a variable number of slots for a plurality of de-interleaving results;

means for soft-combining symbols within each of the plurality of de-interleaving results, except for the de-interleaving result over one slot;

means for decoding the one-slot de-interleaved symbols and the soft-combined symbols associated with each of the plurality of de-interleaving results;

means for checking the decoded symbols for an identifier; and

means for extracting the preamble information from the checked symbol carrying the identifier.