Utility-based radio link assignment in multi-radio heterogeneous networks

Techniques for coordinated use of WiFi and LTE radio links are developed for operator-managed multi-radio heterogeneous networks. In particular, we consider deployments based on integrated small cells with co-located WiFi and LTE interfaces, which allow for tighter coordination between the two interfaces especially when used together with WiFi/LTE capable client devices. The paper develops a utility based framework which optimizes the partitioning of users between WiFi and LTE to improve the aggregate per-cell utility. The resulting link assignment framework is applied to take advantage of the orthogonal WiFi carrier to mitigate cross-tier LTE interference between macro-cells and small-cells. Results show that this technique not only improves system capacity and coverage beyond what is achievable with uncoordinated use of WiFi and LTE, but also preserves macro-cell throughput by reducing the need for macro-cells to mute their transmissions in order to avoid cross-tier interference. We also apply the utility-based assignment framework to improve the on-time throughput across users, which measures the average data rate delivered to a user before its delay deadline. This is an important metric to characterize the quality-of-service achievable for transmitting delay sensitive traffic, such as real-time voice and video. Our results show that accounting for delay sensitivity in the optimization can improve the number of users achieving target on-time throughput by up to 3x, when compared with un-coordinated use of WiFi and LTE interfaces.