On the Impact of Transient Period for Short Transmission Duration

摘要

Low latency is the key not only for improving the user experience of today's applications but also for realizing the emerging critical machine type communication use cases for 5G. In 4G and 5G standardization by 3GPP, shortening the transmission duration has been considered as an important technology for latency reduction in future wireless networks. As the transmission duration is shortened, the period when the signal is not well defined due to RF limitations, will naturally become a larger portion of the overall uplink transmission, unless also shortened. This period, commonly referred to as a transient period, can result in the useful signal being distorted and/or cause interference to other users. This paper investigates the impact of the transient period on LTE uplink transmissions shortened by a factor 7 or 2 compared to legacy LTE. Different approaches are proposed in this paper to reduce the transient period impact. Our link level simulation results show that by reducing the transient period duration from 20 μs to 10 μs, around 1.8 dB signal-to-noise ratio gain can be achieved, considering the operation points for typical mobile broadband services. It is shown that placing the transient period outside the allocated transmission duration is preferred despite increased inter-user interference. Moreover, by using a specific characteristic of the reference signal design, the performance gain can be further improved.