论文标题
通过多跳继电器网络流式擦除代码
Streaming Erasure Codes over Multi-hop Relay Network
论文作者
论文摘要
本文研究了多跳网络的低延迟流码。源是通过一系列继电器将每个跳跃链删除的继电器链将消息(流消息)序列(流消息)传输到目的地。每个源消息都必须在$ t $ time插槽的延迟约束中完美恢复。在任何$ t+1 $ time插槽的滑动窗口中,我们假设$ j $'th hop频道引入的$ n_j $ rasures不超过$ n_j $。 Fong [1]等人得出了单个继电器(三节点网络)的容量。虽然可以使用类似的技术将三节点案例的匡威得出的逆向扩展到任何数量的节点(分析其他链接上删除的情况是连续的),但我们接下来表明,该方案(建议巧妙的符号解码和正向策略)无法直接扩展出巧妙的符号解码和正向策略。三节点网络的编码方案被证明可以实现上限,是``与状态无关的''(即,它不依赖于特定的擦除模式)。尽管这是一个非常理想的属性,但在本文中,我们建议``依赖状态''(即取决于特定擦除模式的方案),并表明它可以达到上限到附加标头的大小。由于正如我们所显示的,因此标头的大小不取决于场的大小,因此随着场地的增加,可实现率和上限之间的差距减小。
This paper studies low-latency streaming codes for the multi-hop network. The source is transmitting a sequence of messages (streaming messages) to a destination through a chain of relays where each hop is subject to packet erasures. Every source message has to be recovered perfectly at the destination within a delay constraint of $T$ time slots. In any sliding window of $T+1$ time slots, we assume no more than $N_j$ erasures introduced by the $j$'th hop channel. The capacity in case of a single relay (a three-node network) was derived by Fong [1], et al. While the converse derived for the three-node case can be extended to any number of nodes using a similar technique (analyzing the case where erasures on other links are consecutive), we demonstrate next that the achievable scheme, which suggested a clever symbol-wise decode and forward strategy, can not be straightforwardly extended without a loss in performance. The coding scheme for the three-node network, which was shown to achieve the upper bound, was ``state-independent'' (i.e., it does not depend on specific erasure pattern). While this is a very desirable property, in this paper, we suggest a ``state-dependent'' (i.e., a scheme which depends on specific erasure pattern) and show that it achieves the upper bound up to the size of an additional header. Since, as we show, the size of the header does not depend on the field size, the gap between the achievable rate and the upper bound decreases as the field size increases.