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US 2003/0154438 A1Published application
Low delay decoding
AssigneeQUALCOMM Incorporated
InventorStein A Lundby
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AssigneeQUALCOMM Incorporated
InventorStein A Lundby
Estimating the term…
A method and apparatus for decoding a frame of interleaved information bits in a communications system, where the decoding of the frame of interleaved information bits may begin before all of the bits in the frame are received at a decoding site. The frame of interleaved information bits has a frame start time and a frame end time. The frame also includes a first fractional segment that has a start time that is the same as the frame start time and an end time that is before the frame end time. Prior to transmission of the frame of interleaved information bits to a decoding site, all bits in the frame are encoded at a code rate R to provide encoded bits, and the encoded bits are positioned in the interleaved frame in accordance with an interleaving pattern that stores bits having a code rate R1 within a first fractional segment of the interleaved frame. In one embodiment, R1=R/a1, and a1 corresponds to the first fractional segment of the frame. At the decoding site, interleaved information bits from the first fractional segment of the frame are initially received, and an attempt is made to decode the frame using information bits from only the first fractional segment of the frame. If this initial decoding attempt is unsuccessful, the system attempts to decode the frame again using information bits from both the first fractional segment of the frame and further information bits located between the end time of the first fractional segment and the frame end time.
A method for reducing frame delay in a communications system, comprising:
A method of interleaving encoded bits into an interleaving pattern for a frame such that the interleaving pattern facilitates early decoding of the frame at a decoding site, the method comprising interleaving encoded bits into at least a first fractional segment of the frame, a second fractional segment of the frame, and a third fractional segment of the frame, wherein the first fractional segment is characterized by a code rate R1, the second fractional segment is characterized by a code rate R2, and the third fractional segment is characterized by a code rate R3 such that the code rate R1 is lower than the code rate R2, the code rate R2 is lower than the code rate R3, and the code rate R3 is lower than a frame code rate R.
A subsystem for reducing frame delay in a communications system, comprising:
A channel interleaver configured to interleave encoded bits into an interleaving pattern for a frame such that the interleaving pattern facilitates early decoding of the frame at a decoding site, wherein the interleaving pattern interleaves encoded bits into at least a first fractional segment of the frame, a second fractional segment of the frame, and a third fractional segment of the frame, such that the first fractional segment is characterized by a code rate R1, the second fractional segment is characterized by a code rate R2, and the third fractional segment is characterized by a code rate R3 and further, the code rate R1 is lower than the code rate R2, the code rate R2 is lower than the code rate R3, and the code rate R3 is lower than a frame code rate R.
A decoder configured to reduce delay in decoding received frames by decoding at a first predetermined time after the start of a frame, wherein the first predetermined time is less than the duration of the frame and the decoder uses only those bits of a first fractional portion of the frame received before the first predetermined time, and if the decoding at the first predetermined time is unsuccessful, then decoding at a second predetermined time after the start of the frame, wherein the second predetermined time is less than the duration of the frame and the decoder uses only those bits received in a second fractional portion of the frame.
Dependencies are inferred from the claim text.