While mobile live video analytics apps require end-to-end latency guarantee for responsiveness and immersiveness, achieving consistent low latency is challenging due to complex fluctuations of wireless channel and scene complexity; for example, latency SLO satisfaction rate drops to as low as 26% in commercial 5G MEC platforms. Prior works mostly focus on either app-only (bitrate, DNN adaptation, or GPU allocation) or RAN-only (radio resource allocation) scheduling, with mutual ignorance of the other side resulting in mismatched scheduling decisions and frequent SLO violations. Coordinating the two schedulers is also challenging, as they are run separately by network and cloud operators with disjoint control. We present ARMA, an end-to-end live video analytics system with app-RAN mutual-awareness for high end-to-end latency SLO satisfaction in MEC. We design a mutually-aware decoupled scheduling mechanism on top of RAN Intelligent Controller (RIC) in Open-RAN architecture that fosters cooperative interaction between the two operators' schedulers while preserving operational proprietaries. We prototype an Open RAN-enabled 5G MEC testbed and evaluate ARMA, showing that ARMA achieves 97% SLO satisfaction rate.

The advent of 5G networks promises to revolutionize real-time applications with its high bandwidth capabilities. Despite this, current real-time applications such as 360-degree video conferencing and intelligent transport systems, which demand high data rates and stringent low latency, often find it difficult to satisfy their QoS needs with a single 5 G connection due to inconsistent bandwidth. As a viable option, multipath transport solutions using multiple 5G connections have emerged with recent technological advancements. In this paper, we explore real-time application performance using MPTCP over 5G multiple connections. Our real-world measurements over MPTCP across major 5G operators in South Korea reveal average frame delays exceeding 213 ms. This delay is much higher than our expectations compared to measurements over single-path TCP (SPTCP) under similar network conditions. We attribute this to the delayed reaction of the MPTCP scheduler, which relies on long-term measurements rather than adapting to recent network conditions. The delayed reaction causes sub-optimal path selection and increased latency. This paper contributes a thorough analysis of MPTCP performance degradation in real-time applications, identifies the limitations of current MPTCP schedulers, and considers potential solutions to improve their responsiveness to achieve better application latency performance.

The ultra-dense network (UDN) is a promising technology that overcomes the instability of high-frequency millimeter wave (mmWave) communication in a cellular network. With a short distance between cells and variability of mmWave, a handover occurs frequently in UDN with mmWave. Hence fast handover is essential to provide reliable service. One of the important things for fast handover is prompt signaling between base stations (BSs) through backhaul. However, conventional handovers assumed backhaul has very short latency with ideal deployment. In practice, with non-ideal latency and deployment of backhaul, handover is delayed for backhaul. We find that this delayed handover led to the performance reduction of TCP, the dominant traffic of nowadays. So we propose a ProSCH, the novel handover scheme that operates on a practical backhaul network while guaranteeing TCP performance. ProSCH reduces a handover interruption time by considering the backhaul latency in the handover signaling process and uses a TCP proxy on BS to forward data without loss after handover. Through extensive ns-3 simulation, we show that ProSCH outperforms conventional schemes in terms of handover interruption time, backhaul load, throughput, and delay.

Mobile users in an ultra-dense millimeter-wave cellular network experience handover events more frequently than in conventional networks, which results in increased service interruption time and performance degradation due to blockages. Multi- connectivity has been proposed to resolve this, and it also extends the coverage of millimeter-wave communications. In this paper, we propose a dual-connection based handover scheme for mobile UEs in an environment where they are connected simultaneously with two millimeter-wave cells to overcome frequent handover problems. This scheme allows a mobile UE to choose its serving link between the two mmWave connections according to the measured SINRs and then the corresponding base stations may forward duplicate packets to the UE. We compare our dual-connection based scheme with a conventional single-connection based scheme through ns-3 simulation. The simulation results show that the proposed scheme significantly reduces handover rate and delay. Therefore, we argue that the dual- connection based scheme helps mobile users achieve performance goals they require in ultra-dense cellular environments.