The　enhancement　of　spectrum　utilization　efficiency　(SUE)　is　a　critical　objective　in　fifth　generation　networks-enabled　Internet　of　Things　(5G-IoT)　for　providing　communication　opportunities　to　plethora　of　5G-IoT　devices　within　the　already　scarce　spectrum.　Cognitive　radio　networks　(CRNs)　with　interweave　and　underlay　modes　are　foreseen　to　achieve　this　objective.　The　interweave　mode　is　adequate　for　legacy　CRNs,　while　the　underlay　mode　is　fitting　for　resource-constrained　CRNs.　As　5G-IoT　is　rapidly　evolving　into　heterogeneous　networks,　CRNs　enabled　by　hybrid　underlay-interweave　mode　(H-mode)　emerge　to　be　the　best　option　for　SUE　enhancement　in　5G-IoT.　In　this　paper,　we　comprehensively　analyze　the　performance　of　H-mode　enabled　CRNs　containing　heterogeneous　users　by　proposing　two　H-mode　schemes,　namely,　primary　user　full　priority　(FP)　and　primary　user　partial　priority　(PP).　The　schemes　consider　secondary　users　(SUs)　with　high　and　low　priorities.　In　FP,　primary　users　(PUs)　have　absolute　priority　in　channel　access　while　in　PP,　SUs　with　certain　attributes　are　immune　from　interruptions.　Additionally,　to　accommodate　interrupted　users,　a　simple　yet　efficient　channel　reservation　algorithm　is　proposed,　which　divides　the　given　channels　into　reserved　and　unreserved　bands.　Using　Markov　chain　modeling,　expressions　are　derived　for　core　SUE　related　performance　metrics　including　service　completion　rate　(SCR),　blocking　probability　(BP),　network　serveability　(NS),　successful　service　completion　probability　(SSCP),　handoff　probability,　and　throughput,　independently　for　PUs　and　all　types　of　SUs.　Performance　of　the　proposed　schemes　is　analyzed　under　varying　channel　failure　rates　and　network　traffic　loads.　Efficacy　of　the　proposed　schemes　is　shown　through　analytical　and　simulation　results　against　state-of-the-art.　Improvements　of　up　to　67%　in　BP　and　83%　in　cost　efficiency　are　recorded　as　compared　to　the　state-of-the-art.　Likewise,　up　to　10%　and　84%　difference　in　PUs＇　and　SUs＇　SSCP,　respectively,　and　up　to　17%　and　93%　difference　in　PUs＇　and　SUs＇　SCR,　respectively,　are　noted.　Similarly,　up　to　85%　performance　difference　in　NS　is　recorded.　Moreover,　up　to　35%　improvement　in　throughput　in　H-mode　is　witnessed.　Lastly,　handoff　probability　is　found　to　be　increased　by　5%.　(C)　2021　Elsevier　B.V.　All　rights　reserved.