{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2021:42OW6HBMNK2EF5AJYAEGYXK3UP","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"88b3df508b102d830963060a71b2383b5569d48785ad46744ea6a433b06fd631","cross_cats_sorted":["eess.SP","math.IT"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"cs.IT","submitted_at":"2021-06-20T15:09:32Z","title_canon_sha256":"97f68f1e1733cdec1141da9efa3cb58663d6f3d3e7945e056293ee2dfb2de8d4"},"schema_version":"1.0","source":{"id":"2106.10709","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2106.10709","created_at":"2026-07-05T02:50:52Z"},{"alias_kind":"arxiv_version","alias_value":"2106.10709v1","created_at":"2026-07-05T02:50:52Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2106.10709","created_at":"2026-07-05T02:50:52Z"},{"alias_kind":"pith_short_12","alias_value":"42OW6HBMNK2E","created_at":"2026-07-05T02:50:52Z"},{"alias_kind":"pith_short_16","alias_value":"42OW6HBMNK2EF5AJ","created_at":"2026-07-05T02:50:52Z"},{"alias_kind":"pith_short_8","alias_value":"42OW6HBM","created_at":"2026-07-05T02:50:52Z"}],"graph_snapshots":[{"event_id":"sha256:959921a235d726c69cb71928fef5ff9800d5153305dd07283483adcb13ae0a71","target":"graph","created_at":"2026-07-05T02:50:52Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"integrity":{"available":true,"clean":true,"detectors_run":[],"endpoint":"/pith/2106.10709/integrity.json","findings":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938","summary":{"advisory":0,"by_detector":{},"critical":0,"informational":0}},"paper":{"abstract_excerpt":"Multiple signal classification (MUSIC) has been widely applied in multiple-input multiple-output (MIMO) receivers for direction-of-arrival (DOA) estimation. To reduce the cost of radio frequency (RF) chains operating at millimeter-wave bands, hybrid analog-digital structure has been adopted in massive MIMO transceivers. In this situation, the received signals at the antennas are unavailable to the digital receiver, and as a consequence, the spatial covariance matrix (SCM), which is essential in MUSIC algorithm, cannot be obtained using traditional sample average approach. Based on our previous","authors_text":"Hongtao Duan, Li You, Wenji Wang, Yinsheng Liu, Yiwei Yan","cross_cats":["eess.SP","math.IT"],"headline":"","license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"cs.IT","submitted_at":"2021-06-20T15:09:32Z","title":"Spatial Covariance Matrix Reconstruction for DOA Estimation in Hybrid Massive MIMO Systems with Multiple Radio Frequency Chains"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2106.10709","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:27c259633a0c57ea1b9098096782ad3323f73b8e00ae70f25f246732b57fd69d","target":"record","created_at":"2026-07-05T02:50:52Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"88b3df508b102d830963060a71b2383b5569d48785ad46744ea6a433b06fd631","cross_cats_sorted":["eess.SP","math.IT"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"cs.IT","submitted_at":"2021-06-20T15:09:32Z","title_canon_sha256":"97f68f1e1733cdec1141da9efa3cb58663d6f3d3e7945e056293ee2dfb2de8d4"},"schema_version":"1.0","source":{"id":"2106.10709","kind":"arxiv","version":1}},"canonical_sha256":"e69d6f1c2c6ab442f409c0086c5d5ba3fe17f2dda69c0f3fd64a89e85a54441f","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"e69d6f1c2c6ab442f409c0086c5d5ba3fe17f2dda69c0f3fd64a89e85a54441f","first_computed_at":"2026-07-05T02:50:52.138635Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-07-05T02:50:52.138635Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"PcaNjXOmbY2zx84m9XAFlSYsc3YdvmzVhoU91FPpgRTwSawc9LzaDn0ujN9NG2iWfMlkjBQUWU1BE+l4JiCpDQ==","signature_status":"signed_v1","signed_at":"2026-07-05T02:50:52.138981Z","signed_message":"canonical_sha256_bytes"},"source_id":"2106.10709","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:27c259633a0c57ea1b9098096782ad3323f73b8e00ae70f25f246732b57fd69d","sha256:959921a235d726c69cb71928fef5ff9800d5153305dd07283483adcb13ae0a71"],"state_sha256":"50406480694fcc4ca8ee956922b1a6299e3bd327dfd454dec5c4dfda0f5d1ba2"}