Perceive as You Receive: Collaborative Perception under Partial Reception

Under tight perception deadlines and fluctuating V2X link conditions, an ego agent may need to produce a perception output before collaborative messages are fully received. We study this practical yet underexplored problem of collaborative perception under partial reception. Existing communication-efficient methods primarily optimize message size and accuracy under full reception, without explicitly prioritizing the early delivery of critical evidence or the effective use of partially received messages. We introduce CoDelta, a collaborative perception framework that couples transmission prioritization with ego-centric fusion under partial reception. The sender organizes compact BEV patch representations into a transmission sequence ordered by task relevance. The receiver combines received patches with ego features to generate local additive updates without reconstructing complete collaborator representations. It then aggregates these updates into the ego BEV and refines the resulting representation to restore spatial coherence. Extensive experiments on OPV2V, V2XSet, and DAIR-V2X demonstrate the effectiveness of CoDelta across varying reception ratios. On OPV2V, CoDelta outperforms PragComm by 14.75 percentage points in [email protected] at a 10% reception ratio. Code will be released upon acceptance.