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§Progressive Edge Growth (PEG) LDPC construction
This implements the algorithm described in Xiao-Yu Hu, E. Eleftheriou and D. M. Arnold, “Regular and irregular progressive edge-growth tanner graphs,” in IEEE Transactions on Information Theory, vol. 51, no. 1, pp. 386-398, Jan. 2005.
The algorithm works by adding edge by edge to the Tanner graph. For each
symbol node, wc check nodes are selected to be joined by edges. Each one
is selected in a different step, and the edge is added to the graph, which
affects subsequent decisions.
To select an edge for the current symbol node, a breadth-first search is done with that node as the root, in order to find the distance from each of check nodes to the root. If there are any check nodes not yet reachable from the root, a node at random is selected among the unreachable nodes that have minimum degree (note that this always happens whenever the first edge is added to a symbol node). If all the check nodes are rechable from the root, the set of nodes of minimum degree among those nodes at maximum distance from the root is selected. A node is picked at random from that set.
This procedure tries to maximize local girth greedily and to fill the check nodes uniformly.
Structs§
- Config
- Configuration for the Progressive Edge Growth construction
Enums§
- Error
- Runtime errors of the PEG construction.
Type Aliases§
- Result
- Result type used to indicate PEG runtime errors.