A Packet Level Steering Solution for Tightly Coupled LWIP Networks

Smartphones make use of either LTE or Wi-Fi interface one at a time. Radio level integration (RLI) architecture such as LTE-Wi-Fi Integration with IPSec tunnel (LWIP) enables both the interfaces to operate simultaneously. The real benefit of aggregation resides in enabling packet level steering of traffic, where the incoming packets to LWIP node will be steered across LTE and Wi-Fi links on per-packet granularity. Such packet-level steering leads to the problem of out-of-order (OOO) delivery of packets to the destination. Such OOO delivery occurs due to variable time incurred in delivering the packets through different links viz., LTE and Wi-Fi, OOO delivery, as mentioned earlier, negatively affects TCP performance and triggers spurious retransmissions. In this work, we propose a novel Dynamic pseudo-In-sequence Delivery Algorithm (DIDA) at LWIP node, which mitigates the effects of OOO delivery problem without requiring any modifications at the source and destination devices. DIDA solution operates at the LWIP node and aggregates multiple radio links effectively. We have formulated the crucial parameter, holding time ‘t’ of DIDA. We have setup a prototype of LWIP using OpenAirInterface (OAI) and experimented DIDA on packet level steering over LTE and Wi-Fi networks. DIDA doubles the TCP throughput achieved as compared to native LWIP.