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sdrforengineers / bookerrata

This is the issues and errata for the "Software Defined Radio for Engineers" book
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Sec 8.4.3 Pg 248: LDPC and IEEE 802.11 #8

Closed solomonbstoner closed 3 years ago

solomonbstoner commented 3 years ago

What does "1944 IEEE 802.11n/ac" mean in the sentence shown below? Does it mean to quote the 802.11n/ac standard as an example of a system that uses LDPC with 1944 as the block length? The closest I found that might suggest so is this paper which says "LDPC decoder chip for (1944,972) QC-LDPC codes in IEEE 802.11n communication system". Not sure if (1944,972) means 1944 as the block length.

Screenshot from 2021-08-22 12-04-31

solomonbstoner commented 3 years ago

Also, there is a typo in the sentence below what the screenshot shows.

need to encode a significant amount of bits compared to the other codes to utilize LPDC LDPC efficiently in many cases.

tfcollins commented 3 years ago

LDPC will use a parity matrix to encode/decode the data. The dimension of the matrices is related to the block size (number of bits). For 802.11 n/ac the matrix is of size (1944,972) I believe.

solomonbstoner commented 3 years ago

I see. So IEEE 802.11n/ac was used as an example of block length 1944. I was confused because I thought "1944 IEEE 802.11n/ac" was a phrase. Thanks Travis!