{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2017:4LC5XQ3XEGEJ5NG4MIZOKSSCPF","short_pith_number":"pith:4LC5XQ3X","canonical_record":{"source":{"id":"1707.03571","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.IT","submitted_at":"2017-07-12T07:20:56Z","cross_cats_sorted":["math.IT"],"title_canon_sha256":"cc639075704dd6a2cfdf4de9cf099148dc1de4b487311b75ae6ae63fdaa8e18c","abstract_canon_sha256":"36d09e6a9b10fc4e3d4ea342257ca1e38075c1d4b133b23e15361c4189065b48"},"schema_version":"1.0"},"canonical_sha256":"e2c5dbc37721889eb4dc6232e54a427970d867d7484d09ffc31b02cce01a5c87","source":{"kind":"arxiv","id":"1707.03571","version":2},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1707.03571","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"arxiv_version","alias_value":"1707.03571v2","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1707.03571","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"pith_short_12","alias_value":"4LC5XQ3XEGEJ","created_at":"2026-05-18T12:31:00Z"},{"alias_kind":"pith_short_16","alias_value":"4LC5XQ3XEGEJ5NG4","created_at":"2026-05-18T12:31:00Z"},{"alias_kind":"pith_short_8","alias_value":"4LC5XQ3X","created_at":"2026-05-18T12:31:00Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2017:4LC5XQ3XEGEJ5NG4MIZOKSSCPF","target":"record","payload":{"canonical_record":{"source":{"id":"1707.03571","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.IT","submitted_at":"2017-07-12T07:20:56Z","cross_cats_sorted":["math.IT"],"title_canon_sha256":"cc639075704dd6a2cfdf4de9cf099148dc1de4b487311b75ae6ae63fdaa8e18c","abstract_canon_sha256":"36d09e6a9b10fc4e3d4ea342257ca1e38075c1d4b133b23e15361c4189065b48"},"schema_version":"1.0"},"canonical_sha256":"e2c5dbc37721889eb4dc6232e54a427970d867d7484d09ffc31b02cce01a5c87","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:33:34.593500Z","signature_b64":"wd4RjkoRng1t8R1xBmlf8JsmjVftNxXPmibQvQ+sD2lYNpGet4wubgy4hVz4EvWmN2BkoVthfdVe7ZtCeHGjCg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"e2c5dbc37721889eb4dc6232e54a427970d867d7484d09ffc31b02cce01a5c87","last_reissued_at":"2026-05-18T00:33:34.592952Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:33:34.592952Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1707.03571","source_version":2,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:33:34Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ipLWbDt0z/fkFxDLt/e2CpbUHiZQ5lvH+cqoHRDKYFtNpD1JXP6wnl7ANRjrMInxJi5TN/ttkY7M/kqsqIuIDg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-24T19:18:43.429089Z"},"content_sha256":"989a4f4e56311091e833f98893f2b71e52966137119a855a27314e5a596a1985","schema_version":"1.0","event_id":"sha256:989a4f4e56311091e833f98893f2b71e52966137119a855a27314e5a596a1985"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2017:4LC5XQ3XEGEJ5NG4MIZOKSSCPF","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Enhancing massive MIMO: A new approach for Uplink training based on heterogeneous coherence time","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["math.IT"],"primary_cat":"cs.IT","authors_text":"Maialen Larra\\~naga, Mohamad Assaad, Salah Eddine Hajri","submitted_at":"2017-07-12T07:20:56Z","abstract_excerpt":"Massive multiple-input multiple-output (MIMO) is one of the key technologies in future generation networks. Owing to their considerable spectral and energy efficiency gains, massive MIMO systems provide the needed performance to cope with the ever increasing wireless capacity demand. Nevertheless, the number of scheduled users stays limited in massive MIMO both in time division duplexing (TDD) and frequency division duplexing (FDD) systems. This is due to the limited coherence time, in TDD systems, and to limited feedback capacity, in FDD mode. In current systems, the time slot duration in TDD"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1707.03571","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:33:34Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"JpgB0rKYFoN4y4nGlXlT9CWUu23yzmwZorOxUKcqrPe4yYYYFBq2BkMZqDv4cS67iH8r26h7N9oP3Lr62jtcAg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-24T19:18:43.429465Z"},"content_sha256":"cf908db5638e9365ad05e111560eeffae7b66c82c4ecb17699c0aa8722d8eb8d","schema_version":"1.0","event_id":"sha256:cf908db5638e9365ad05e111560eeffae7b66c82c4ecb17699c0aa8722d8eb8d"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/bundle.json","state_url":"https://pith.science/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-06-24T19:18:43Z","links":{"resolver":"https://pith.science/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF","bundle":"https://pith.science/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/bundle.json","state":"https://pith.science/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/state.json","well_known_bundle":"https://pith.science/.well-known/pith/4LC5XQ3XEGEJ5NG4MIZOKSSCPF/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2017:4LC5XQ3XEGEJ5NG4MIZOKSSCPF","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":"36d09e6a9b10fc4e3d4ea342257ca1e38075c1d4b133b23e15361c4189065b48","cross_cats_sorted":["math.IT"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.IT","submitted_at":"2017-07-12T07:20:56Z","title_canon_sha256":"cc639075704dd6a2cfdf4de9cf099148dc1de4b487311b75ae6ae63fdaa8e18c"},"schema_version":"1.0","source":{"id":"1707.03571","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1707.03571","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"arxiv_version","alias_value":"1707.03571v2","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1707.03571","created_at":"2026-05-18T00:33:34Z"},{"alias_kind":"pith_short_12","alias_value":"4LC5XQ3XEGEJ","created_at":"2026-05-18T12:31:00Z"},{"alias_kind":"pith_short_16","alias_value":"4LC5XQ3XEGEJ5NG4","created_at":"2026-05-18T12:31:00Z"},{"alias_kind":"pith_short_8","alias_value":"4LC5XQ3X","created_at":"2026-05-18T12:31:00Z"}],"graph_snapshots":[{"event_id":"sha256:cf908db5638e9365ad05e111560eeffae7b66c82c4ecb17699c0aa8722d8eb8d","target":"graph","created_at":"2026-05-18T00:33:34Z","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"},"paper":{"abstract_excerpt":"Massive multiple-input multiple-output (MIMO) is one of the key technologies in future generation networks. Owing to their considerable spectral and energy efficiency gains, massive MIMO systems provide the needed performance to cope with the ever increasing wireless capacity demand. Nevertheless, the number of scheduled users stays limited in massive MIMO both in time division duplexing (TDD) and frequency division duplexing (FDD) systems. This is due to the limited coherence time, in TDD systems, and to limited feedback capacity, in FDD mode. In current systems, the time slot duration in TDD","authors_text":"Maialen Larra\\~naga, Mohamad Assaad, Salah Eddine Hajri","cross_cats":["math.IT"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.IT","submitted_at":"2017-07-12T07:20:56Z","title":"Enhancing massive MIMO: A new approach for Uplink training based on heterogeneous coherence time"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1707.03571","kind":"arxiv","version":2},"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":"sha256:989a4f4e56311091e833f98893f2b71e52966137119a855a27314e5a596a1985","target":"record","created_at":"2026-05-18T00:33:34Z","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":"36d09e6a9b10fc4e3d4ea342257ca1e38075c1d4b133b23e15361c4189065b48","cross_cats_sorted":["math.IT"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.IT","submitted_at":"2017-07-12T07:20:56Z","title_canon_sha256":"cc639075704dd6a2cfdf4de9cf099148dc1de4b487311b75ae6ae63fdaa8e18c"},"schema_version":"1.0","source":{"id":"1707.03571","kind":"arxiv","version":2}},"canonical_sha256":"e2c5dbc37721889eb4dc6232e54a427970d867d7484d09ffc31b02cce01a5c87","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"e2c5dbc37721889eb4dc6232e54a427970d867d7484d09ffc31b02cce01a5c87","first_computed_at":"2026-05-18T00:33:34.592952Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:33:34.592952Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"wd4RjkoRng1t8R1xBmlf8JsmjVftNxXPmibQvQ+sD2lYNpGet4wubgy4hVz4EvWmN2BkoVthfdVe7ZtCeHGjCg==","signature_status":"signed_v1","signed_at":"2026-05-18T00:33:34.593500Z","signed_message":"canonical_sha256_bytes"},"source_id":"1707.03571","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:989a4f4e56311091e833f98893f2b71e52966137119a855a27314e5a596a1985","sha256:cf908db5638e9365ad05e111560eeffae7b66c82c4ecb17699c0aa8722d8eb8d"],"state_sha256":"e1baac4dfdf762d6526aa945267bc56d5a7d3709b88b228edc9e99cbbef27755"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"nEpP2ZBMuhfefyP30uRC3lPrUhtM/40ImeGP4kjWOOoSRx2+LIusBtl/7DF/eEizA7rPcMj0/b/pwBqzXjREAA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-06-24T19:18:43.431405Z","bundle_sha256":"ed214c04d68a1bc8561ae6d42b6c88a6c51043b5b7cc8c83ce8095d82bbca0d4"}}