5G physical random access channel (PRACH) will use new preamble formats based on short Zadoff-Chu (ZC) sequences to enable new use cases. These formats result however in a PRACH capacity shortfall where the number of sequences available for network planning may just be enough to support few cells without sequence reuse. To overcome this issue, two enlarged constant-amplitude sequence constructions that include ZC sequences, and thus being backward-compatible with the current 5G PRACH design, are presented. Both constructions feature a desirable subset structure from which follows a natural cellular network sequence allocation where each cell-specific sequence subset has a controllable low-correlation zone similar to ZC sequences, and thus enables a similar detection performance inside a cell. The two extensions are meanwhile structurally different and offer different network allocations, as for one, new sequences are distributed among all cells, while for the other, they are in separated cells. With both proposed supersets and the new 5G PRACH formats, hundred-times more cells without sequence reuse can be supported compared to ZC sequences for a moderately larger inter-cell correlation than intra-cell correlation. Simulation results confirm that using the proposed supersets instead of reusing sequences in the network can significantly improve detection performance.

中文翻译：

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克服 5G PRACH 容量不足：具有低相关区的 Zadoff-Chu 序列的超集

5G 物理随机接入信道 (PRACH) 将使用基于短 Zadoff-Chu (ZC) 序列的新前导格式来实现新用例。然而，这些格式导致 PRACH 容量不足，其中可用于网络规划的序列数量可能刚好足以支持少数小区而无需序列重用。为了克服这个问题，提出了两个扩大的恒定幅度序列结构，包括 ZC 序列，因此与当前的 5G PRACH 设计向后兼容。两种结构都具有理想的子集结构，其遵循自然的蜂窝网络序列分配，其中每个特定于小区的序列子集具有类似于 ZC 序列的可控低相关区域，因此能够在小区内实现类似的检测性能。同时，这两种扩展在结构上不同，提供不同的网络分配，一种是将新序列分布在所有小区中，而另一种是在分离的小区中。使用提议的超集和新的 5G PRACH 格式，与 ZC 序列相比，可以支持数百倍的没有序列重用的小区，以实现比小区内相关性更大的小区间相关性。仿真结果证实，在网络中使用所提出的超集而不是重用序列可以显着提高检测性能。与 ZC 序列相比，对于比小区内相关性稍大的小区间相关性，可以支持数百倍的没有序列重用的小区。仿真结果证实，在网络中使用所提出的超集而不是重用序列可以显着提高检测性能。与 ZC 序列相比，对于比小区内相关性稍大的小区间相关性，可以支持数百倍的没有序列重用的小区。仿真结果证实，在网络中使用所提出的超集而不是重用序列可以显着提高检测性能。