mmHandover

With the increase of data driven vehicular applications, existing networks cannot satisfy the communication requirements. Therefore, 5G millimeter wave (mmWave) communications, which can offer multi-gigabit data rate, hold potential to be utilized in vehicular networks. On one hand, due to the densely deployed 5G base stations, frequent handover will largely decrease the quality of service, where recent handover is at hundred-millisecond level. On the other hand, mmWave links are easily broken by obstacles because of short wavelength. Yet existing handover protocols do not consider the blockage problem, which frequently occurs in mmWave based networks. To address these problems, we propose a real-time handover protocol called mmHandover for 5G mmWave vehicular networks leveraging mmWave antennae. In mmHandover, multiple antennae in one array are divided into two parts: pre-connected antennae and data transmission antennae. In parallel, pre-connected antennae build the connection with multiple candidate base stations before activation based on a designed pre-connection strategy, while data transmission antennae are responsible for data delivery with the currently connected base station. When handover is triggered or blockage happens, one of the pre-connected links will convert into data transmission link, thus realizing almost seamless handover. Finally, real data-driven simulations demonstrate the efficiency and effectiveness of mmHandover. Compared with standard 4G/WiFi handover protocols, mmHandover greatly reduces the delay from more than 5000µs to about 1000µs. Besides, the delay gap will get widened coupled with increase in the number of vehicles.