ing schemes. If the implementation requirement is to support very low energy consumption, LDPC has the capability of realizing that with physically optimized circuits. Likewise, the same LDPC code can be used with full parallelized implementations if the objective is to achieve high throughputs. LDPC implementations can also support finer granularity of block sizes and code rates. LDPC has different design flavors, and each offers different benefits. It is well understood that quasi-cyclic (QC) LDPC codes are the most realistic type and provides lower encoding/decoding complexities compared to other variants. This variant is 6.13 Channel Coding with 5G Higher code rate PCM Lower code rate 1 2 3 4 5 6 7 8 9 11213141516 Figure 6.46 Support for different rates in 5G LDPC base graph #1 already used in standards like IEEE 802.11ac, IEEE 802.11ad, IEEE 802.11a/b/g/n, IEEE 802.15.3c, IEEE 802.1e, DVB C2/S2/T2, etc. 5G channel coding is also based on these QC-LDPC codes. However, compared to many other variants of LDPC codes standardized in the past, 5G supports finer granularity of block sizes, code rates, and incremental redundancy (IR) HARQ. For example, IEEE 802.11n only defines fixed code rates and block sizes in the LDPC design and supports only 12 combinations, but 5G LDPC design construction supports 1-bit granularity of block sizes, IR-HARQ, and all practical code rates by utilizing two base graphs. LDPC design in 5G is a rate-compatible design, where higher to lower code rates are supported by extending the same base graph. Figure 6.46 shows the structure of the first base graph used in 5G, where the part shown in a smaller box is represents a higher code rate transmission, and the part in the larger box represents a lower code rate transmission. In this type of design, incremental parity bits can be generated based on the information bits with the encoding with a lower code rate parity check matrix (PCM) and using different parts of the encoded bits in each transmission; those bits can be decoded with the matc