Maximum Bandwidth Allocation Ratio for Scheduled Traffic in IEEE 802.1 TSN

Abstract

The Control Area Network (CAN) protocol is widely used in In-Vehicle Network (IVN). However the bandwidth of the CAN protocol is not appropriate for infotainment services or Advanced Driver Assisted Systems (ADASs). IEEE 802.1 Audio Video Bridging (AVB) has been recently adopted for vehicle applications to overcome the bandwidth problem. Nonetheless, AVB cannot be used for the control traffic. The control traffic should meet the ultra-low latency requirement which is less than 100 μs over 5 hops. Since 2013, IEEE 802.1 Time Sensitive Network (TSN) has been being developed to overcome these problems. One of the standards in TSN is defined for the scheduled traffic class. The scheduled traffic is based on the time-triggered communication which can be used for the control traffic in vehicles. Unfortunately, specific details of the standard such as proper frame sizes and transfer intervals have not been defined yet. In this paper, mathematical analysis and simulation were done for finding the proper frame size and minimum transfer interval of the scheduled traffic to solve above problems. The maximum frame size of the scheduled traffic is found to be 157 bytes for satisfying the ultra-low latency requirement. The minimum transfer interval of the scheduled traffic is also found to be 155 μs for satisfying other traffic transmission. Finally, the allocation ratio of the bandwidth for the scheduled traffic was calculated to be 8%. Also, it was verified by simulation.|Control Area Network (CAN) 프로토콜은 차량 내 네트워크 (IVN)에서 널리 사용되고 있다. 하지만 CAN 프로토콜의 대역폭은 인포테인먼트 혹은 첨단 운전자 보조 시스템 (ADAS)에 사용하기 적합하지 못하다. IEEE 802.1 Audio Video Bridging (AVB)는 차량 어플리케이션 사용으로 인한 부족한 대역폭 문제를 극복하기 위하여 개발되고 있다. 하지만 AVB는 제어 트래픽을 위해서 사용할 수 없다. 제어 트래픽은 5홉 동안 100 μs 이내의 지연인 ultra-low 지연을 만족해야 한다. 2013년, AVB는 IEEE 802.1 Time Sensitive Network (TSN)으로 개선되었다. TSN 표준들 중 하나에서 스케줄 트래픽을 정의하고 있다. 차량의 제어 트래픽을 위해서 사용할 수 있는 스케줄 트래픽은 time-triggered 통신을 기반으로 한다. 하지만 스케줄 트래픽에 대한 구체적인 프레임 크기와 전송 간격은 아직 정의되지 않은 상황이다. 본 논문에서는 위의 문제들을 해결하기 위하여 스케줄 트래픽의 적합한 프레임 크기와 전송 간격을 찾기 위하여 수학적 계산과 시뮬레이션을 수행하였다. Ultra-low 지연 요구사항을 만족하는 스케줄 트래픽의 최대 프레임 크기는 157 bytes이다. 또한 다른 트래픽의 전송을 보장할 수 있는 스케줄 트래픽의 최소 전송 간격은 155 μs이다. 결과 값을 토대로 스케줄 트래픽을 위한 대역폭의 최적 할당 비율은 8%임을 시뮬레이션을 통해 검증하였다.; The Control Area Network (CAN) protocol is widely used in In-Vehicle Network (IVN). However the bandwidth of the CAN protocol is not appropriate for infotainment services or Advanced Driver Assisted Systems (ADASs). IEEE 802.1 Audio Video Bridging (AVB) has been recently adopted for vehicle applications to overcome the bandwidth problem. Nonetheless, AVB cannot be used for the control traffic. The control traffic should meet the ultra-low latency requirement which is less than 100 μs over 5 hops. Since 2013, IEEE 802.1 Time Sensitive Network (TSN) has been being developed to overcome these problems. One of the standards in TSN is defined for the scheduled traffic class. The scheduled traffic is based on the time-triggered communication which can be used for the control traffic in vehicles. Unfortunately, specific details of the standard such as proper frame sizes and transfer intervals have not been defined yet. In this paper, mathematical analysis and simulation were done for finding the proper frame size and minimum transfer interval of the scheduled traffic to solve above problems. The maximum frame size of the scheduled traffic is found to be 157 bytes for satisfying the ultra-low latency requirement. The minimum transfer interval of the scheduled traffic is also found to be 155 μs for satisfying other traffic transmission. Finally, the allocation ratio of the bandwidth for the scheduled traffic was calculated to be 8%. Also, it was verified by simulation.