Contention resolution addresses the problem of coordinating access to a shared channel. Time proceeds in slots, and a packet transmission can be made in any slot. A packet is successfully sent if no other packet is also transmitted during that slot. If two or more packets are sent in the same slot, then none of these transmissions succeed. Listening during a slot gives ternary feedback, indicating if that slot had (0) silence, (1) a successful transmission, or (2+) noise. No other feedback is available. Packets are (adversarially) injected into the system over time. A packet departs the system once it is successful. The goal is to send all packets while optimizing throughput, which is roughly the fraction of successful slots. Most prior algorithms with constant throughput require a short feedback loop, in the sense that a packet's sending probability in slot t+1 is fully determined by its internal state at slot t and the channel feedback at slot t. An open question is whether these short feedback loops are necessary; that is, how often must listening and updating occur in order to achieve constant throughput? This question addresses energy efficiency, since both listening and sending consume significant energy. The channel can also suffer adversarial noise ("jamming"), which causes any listener to hear noise, even when no packets are sent. How does jamming affect our goal of long feedback loops/energy efficiency? Connecting these questions, we ask: what does a contention-resolution algorithm have to sacrifice to reduce channel accesses? Must we give up on constant throughput or robustness to noise? Here, we show that we need not concede anything. Suppose there are N packets and J jammed slots, where the input is determined by an adaptive adversary. We give an algorithm that, with high probability in N+J, has constant throughput and polylog(N+J) channel accesses per packet.

翻译：竞争解决旨在协调对共享信道的访问。时间按时间槽划分，报文可在任意时间槽内传输。若某时间槽内无其他报文同时传输，则该报文成功发送；若同一时间槽内发送两个或多个报文，则所有传输均失败。监听时间槽可获得三元反馈，指示该槽为（0）静默、（1）成功传输或（2+）噪声，且无其他可用反馈。报文随时间（对抗性）注入系统，成功发送后即退出系统。目标是在优化吞吐量（大致为成功时间槽占比）的同时发送所有报文。以往大多数恒定吞吐量算法需要短反馈环路，即报文在t+1时间槽的发送概率完全由其t时刻内部状态及t时刻信道反馈决定。一个开放问题是：短反馈环路是否必要？换言之，为达到恒定吞吐量，监听和更新需以何种频率进行？由于监听和发送均消耗大量能量，该问题涉及能效。信道还可能遭受对抗性噪声（"干扰"），导致即使无报文发送，监听者也会听到噪声。干扰如何影响我们实现长反馈环路/能效的目标？关联这些问题，我们提出：竞争解决算法需牺牲何物来减少信道访问？是否必须放弃恒定吞吐量或抗噪性？本文证明无需任何妥协。假设存在N个报文和J个干扰时间槽，输入由自适应对抗者决定。我们提出一种算法，在N+J的高概率下，可实现恒定吞吐量且每个报文仅需多对数(N+J)次信道访问。