Next-generation internet-of-things (IoT) networks require extremely low latency, complexity, and collision probability. We introduce the novel partial-information multiple access (PIMA) scheme, a semi-grant-free (GF) coordinated random access (RA) protocol for short packet transmission, with the aim of reducing the latency and packet loss of traditional multiple access schemes, as well as more recent preamble-based schemes. With PIMA, the base station (BS) acquires partial information on instantaneous traffic conditions in the partial information acquisition (PIA) sub-frame, estimating the number of active devices, i.e., having packets waiting for transmission in their queue. Based on this estimate, the BS chooses both the total number of slots to be allocated in the data transmission (DT) sub-frame and the respective user-to-slot assignment. Although collisions may still occur due to multiple users assigned to the same slot, they are drastically reduced with respect to the slotted ALOHA (SALOHA) scheme, while achieving lower latency than both time-division multiple-access (TDMA) and preamble-based protocols, due to the extremely reduced overhead of the PIA sub-frame. Finally, we analyze and assess the performance of PIMA under various activation statistics, proving the robustness of the proposed solution to the intensity of traffic, also with burst traffic.

翻译：下一代物联网网络要求极低的延迟、复杂度和碰撞概率。本文提出新型部分信息多址接入方案，这是一种面向短包传输的半免授权协调随机接入协议，旨在降低传统多址接入方案及近期基于前导码方案的延迟与丢包率。在该方案中，基站通过部分信息获取子帧获取瞬时流量状况的部分信息，估计活跃设备数量（即队列中有待传输数据包的设备）。基于此估计值，基站同时选择数据传输子帧中需分配的时隙总数及相应的用户-时隙分配方案。尽管多用户分配至同一时隙仍可能发生碰撞，但其碰撞概率相比分时ALOHA方案已显著降低；同时，由于PIA子帧开销极低，该方案的延迟既低于时分多址协议，也低于基于前导码的协议。最后，本文在不同激活统计特征下分析并评估了PIMA的性能，验证了所提方案对流量强度（包括突发流量）的鲁棒性。