LFTA: Legacy Friendly Traffic Allocation Strategy for Multi-Link Operation in WiFi7

IEEE 802.11be introduces MLO (Multi-Link Operation), where a device can use multiple links/interfaces such as 2.4, 5, and 6 GHz bands simultaneously. A device capable of performing MLO is called MLD (Multi-Link Device) and can transmit data using aggregated bandwidth. To take advantage of MLO, the traffic must be divided intelligently among multiple available interfaces. While doing so, it is important to ensure co-existence with non-MLO/legacy devices. We propose a flow allocation approach, LFTA (Legacy Friendly rate and congestion aware Traffic Allocation at flow arrivals). It allocates flows of MLDs till only a certain limit so as to spare channel capacity exclusively for single-link non-MLO devices. While allocating flows, it considers link occupancy and rate of the links. LFTA allows intelligent allocation of traffic for MLD devices in a legacy-friendly way and also leads to a balanced load distribution across different interfaces. We compare the performance of LFTA with baselines proposed in the prior work by simulating MLO operation. LFTA outperforms the baselines by allocating about 23%/49% more legacy flows for sparse and about 20%/74% more legacy flows for dense deployment compared to the best/worst performing baseline approach with no/minimal impact on MLO devices.