Bit-interleaved　coded　modulation　with　iterative　decoding　(BICM-ID)　is　a　key　technology　enabling　the　communication　systems　to　realize　reliable　and　efficient　data　transmission.　In　this　work,　we　present　a　study　on　the　adaptive　irregular-mapping　(AIM)-aided　BICM-ID　systems　with　the　use　of　protograph　low-density　parity-check　(PLDPC)　codes.　To　be　specific,　we　first　propose　a　three-step　design　strategy　to　generate　a　type　of　adaptive　constellations,　which　can　be　combined　with　their　corresponding　initial　constellations　to　formulate　an　AIM　scheme　for　improving　the　BICM-ID　performance.　Then,　we　put　forward　a　theoretical-analysis　tool,　called　AIM-based　protograph　extrinsic　information　transfer　(PEXIT)　algorithm,　to　estimate　the　convergence　performance　of　PLDPC　codes　in　the　AIM-aided　BICM-ID　systems.　By　making　use　of　such　an　algorithm,　we　further　develop　a　code-design　method　to　construct　a　new　type　of　PLDPC　codes,　called　enhanced　PLDPC　codes,　tailored　for　the　AIM-aided　BICM-ID　systems.　Both　convergence　analysis　and　simulations　indicate　that　the　proposed　AIM-aided　BICM-ID　systems　perform　better　than　the　existing　counterparts,　and　their　performance　can　be　significantly　improved　by　using　the　enhanced　PLDPC　codes.　Consequently,　the　proposed　designs　have　great　potential　to　meet　the　high-reliability,　high-throughput,　and　strong　link-adaptation　requirements　of　future　wireless-communication　scenarios,　such　as　green　Internet　of　Things　(IoT).