As a key pillar technology for the future 6G networks, terahertz (THz) communication can provide high-capacity transmissions, but suffers from severe propagation loss and line-of-sight (LoS) blockage that limits the network coverage. Narrow beams are required to compensate for the loss, but they in turn bring in beam misalignment challenge that degrades the THz network performance. The high sensing accuracy of THz signals enables integrated sensing and communication (ISAC) technology to assist the LoS blockage and user mobility-induced beam misalignment, enhancing THz network coverage. In line with the 5G beam management, we propose a joint synchronization signal block (SSB) and reference signal (RS)-based sensing (JSRS) scheme to predict the need for beam switches, and thus prevent beam misalignment. We further design an optimal sensing signal pattern that minimizes beam misalignment with fixed sensing resources, which reveals design insights into the time-to-frequency allocation. We derive expressions for the coverage probability and spatial throughput, which provide instructions on the ISAC-THz network deployment and further enable evaluations for the sensing benefit in THz networks. Numerical results show that the JSRS scheme is effective and highly compatible with the 5G air interface. Averaged in tested urban use cases, JSRS achieves near-ideal performance and reduces around 80% of beam misalignment, and enhances the coverage probability by about 75%, compared to the network with 5G-required positioning ability.

翻译：作为未来6G网络的关键支柱技术，太赫兹通信能够提供高容量传输，但面临严重的传播损耗和视距阻塞问题，限制了网络覆盖范围。为补偿损耗需要窄波束，但这又带来波束失准挑战，从而降低太赫兹网络性能。太赫兹信号的高感知精度使得集成感知与通信技术能够辅助解决视距阻塞和用户移动性导致的波束失准问题，从而增强太赫兹网络覆盖。结合5G波束管理框架，我们提出一种联合同步信号块与参考信号感知方案，用于预测波束切换需求，进而防止波束失准。进一步设计了最优感知信号模式，在固定感知资源下最小化波束失准，揭示了时频资源分配的优化思路。推导了覆盖概率和空间吞吐量的表达式，为ISAC-太赫兹网络部署提供指导，并可评估太赫兹网络中感知技术的收益。数值结果表明，该方案有效且与5G空中接口高度兼容。在测试的城市用例中，平均而言，与具备5G标准定位能力的网络相比，JSRS方案实现了接近理想的性能，减少约80%的波束失准，并将覆盖概率提升约75%。