P-BSR enhancements for IAB networks to improve E2E latency

Systems and methods for enhancing the use of pre-emptive buffer status reports (pre-BSRs) in wireless communications systems implementing integrated access and backhaul (IAB) networks are disclosed herein. In some cases, an IAB node can re-classify the LCGs of one or more incoming data flows according to such pre-BSR usage. This may involve the use of and extended medium access control (MAC) control element (MAC CE) having more LCG bits than previously contemplated, having sub-LCG bits, or that includes further LCG classification information bits. Other embodiments use a priority index for LCGs in an extended pre-BSR MAC CE. The priority index may include one or more of a priority field, a prioritized bit rate (PBR), and/or a bucket size duration (BSD) that is reported to an IAB donor. Other embodiments leverage the provision of additional grants from an IAB node to a child IAB node to reduce unwanted pre-BSR effects.