mmWave networks promise high bandwidth but face significant challenges in maintaining reliable connections for users moving at high speed. Frequent handovers, complex beam alignment, and signal blockage from car bodies lead to service interruptions and degraded performance. We present Wall-Street, a vehicle-mounted smart surface that enhances mmWave connectivity for in-vehicle users. Wall-Street improves mobility management by (1) steering outdoor mmWave signals into the vehicle for shared coverage and providing a single, collective handover for all users; (2) performing neighbor-cell search without interrupting data transfer, ensuring seamless handovers; and (3) connecting users to a new cell before disconnecting from the old cell for reliable cell transitions. We implemented and integrated Wall-Street into the COSMOS testbed. We collected PHY traces with multiple base station nodes and in-vehicle user nodes with a surface-mounted vehicle, driving on a nearby road. Our trace-driven ns-3 simulation demonstrates a throughput im- provement of up to 78% and a latency reduction of up to 34% over the standard Standalone handover scheme.

翻译：毫米波网络虽能提供高带宽，但在为高速移动用户维持可靠连接方面面临重大挑战。频繁的切换、复杂的波束对准以及车体造成的信号遮挡，导致服务中断和性能下降。我们提出Wall-Street，一种车载智能表面，旨在增强车内用户的毫米波连接性。Wall-Street通过以下方式改进移动性管理：(1) 将室外毫米波信号引导至车内，实现共享覆盖，并为所有用户提供单一、集体的切换；(2) 在不中断数据传输的情况下执行邻区搜索，确保无缝切换；(3) 在从旧小区断开连接之前将用户连接到新小区，以实现可靠的小区转换。我们将Wall-Street实现并集成到COSMOS测试平台中。我们使用多基站节点和一辆表面安装该系统的车辆内的用户节点，在附近道路上行驶，收集了物理层（PHY）轨迹。基于轨迹的ns-3仿真表明，与标准的独立切换方案相比，吞吐量最高可提升78%，延迟最高可降低34%。