Enhanced Interference Management for 6G in-X Subnetworks

Short-range low-power 6th generation (6G) in-X subnetworks are proposed as a viable radio concept for supporting extreme communication requirements in emerging applications such as wireless control of robotic arms and control of critical on-body devices, e.g. wireless heart pacemaker. For these applications, ultra-high reliability (e.g., above 6 nines) with sub-ms latency must be guaranteed at all spatio-temporal instants. To meet these requirements, radio systems that are robust against fading and interference are crucial. In this paper, we present a comprehensive investigation on technology enablers and techniques for interference mitigation in 6G in-X subnetworks. We present several techniques including blind-repetition with pseudo-random frequency hopping and environment-aware mechanisms for interference management via dynamic channel allocation. We further propose two novel enhancements viz: (1) repetition order adaptation involving real-time selection of the number of repetitions based on current channel conditions; and (2) anticipatory packet duplication in which each subnetwork duplicates its transmission on a secondary channel group whenever it detects the presence of a potentially harmful neighbouring subnetwork. We perform extensive simulations in an industrial factory environment with mobile in-X subnetworks using models and parameters defined by the 3rd Generation Partnership Project (3GPP). Results show that in-X subnetworks requires large bandwidth (≥ 1 GHz), up to 2 packet repetitions and environment-aware interference coordination in order to support packet loss rate below 10 −6 with a latency < 100~\mu \text{s} . The number of repetitions can however be reduced for systems with survival time greater than the cycle time. The proposed enhancements also result in up to \times 10^{4} packet loss rate reduction for systems with survival time above 2 cycle times.