Systems and methods for parallel dual-mode turbo decoders

A method of decoding using a turbo decoder comprising N MAP engines and N extrinsic memory banks accessible by each of the N MAP engines, wherein the N extrinsic memory banks, the method comprising:

• in a first half of a decoding iteration, the N MAP engines read a first dataset from the N extrinsic memory banks in natural row and column order;
• in the first half of a decoding iteration, the N MAP engines write a second dataset to the N extrinsic memory banks in natural row and column order;
• in a second half of a decoding iteration, the N map engines read a third dataset to the N extrinsic memory banks in a predetermined row and column order in accordance with an interleaver table;
• and
• in the second half of a decoding iteration, the N map engines write a fourth dataset to the N extrinsic memory banks in the predetermined row and column order, wherein the N map engines writing the fourth dataset to the N extrinsic memory banks further comprises:
• for k=1, 2, 3, 4 . . . N, concurrently each kth MAP engine of the N MAP engines writing the fourth dataset in parallel to the corresponding kth column of the write column buffer.

A turbo decoder comprising:

• a plurality of maximum a posteriori (MAP) engines;
• a plurality of extrinsic memory banks accessible by a MAP engine of the plurality of MAP engines;
• wherein the turbo decoder is configured to operate in a High-Speed Packet Access (HSPA) mode and a Long Term Evolution (LTE) mode;
• wherein when the turbo decoder is operating in HSPA mode the plurality of extrinsic memory banks is configured such that during a first half of a decoding iteration, the MAP engine is able to read a first dataset from and write second dataset to the plurality of extrinsic memory banks in natural row and column order, and during a second half of the decoding iteration, the MAP engine is able to read a third dataset from and write a fourth dataset to the plurality of extrinsic memory banks in a predetermined row and column order in accordance with an HSPA interleaver table.