Imola: A decentralised learning-driven protocol for multi-hop White-Fi

Abstract

In this paper we tackle the digital exclusion problem in developing and remote locations by proposing Imola, an inexpensive learning-driven access mechanism for multi-hop wireless networks that operate across TV white-spaces (TVWS). Stations running Imola only rely on passively acquired neighbourhood information to achieve scheduled-like operation in a decentralised way, without explicit synchronisation. Our design overcomes pathological circumstances such as hidden and exposed terminals that arise due to carrier sensing and are exceptionally problematic in low frequency bands. We present a prototype implementation of our proposal and conduct experiments in a real test bed, which confirms the practical feasibility of deploying our solution in mesh networks that build upon the IEEE 802.11af standard. Finally, the extensive system level simulations we perform demonstrate that Imola achieves up to 4x\u97 more throughput than the channel access protocol defined by the standard and reduces frame loss rate by up to 100%

ORLA/OLAA: Orthogonal Coexistence of LAA and WiFi in Unlicensed Spectrum

“…duration of idle/busy periods via open source firmware [26]) and have been used to develop custom features (e.g. precise control of TX engine timings [27] [27], which the LTE protocol stack can periodically inspect. In case of synchronous LBT operation, the 802.11 interface can also be instructed by writing into the shared memory, to immediately generate a CTS-to-self frame that reserves the channel for the desired duration.…”

“…duration of idle/busy periods via open source firmware [26]) and have been used to develop custom features (e.g. precise control of TX engine timings [27]). For our design, key functionality can be implemented as follows.…”

“…(3) Detecting LIFS opportunities: To avoid collisions, an LBT WN has to detect if a channel has been idle for LIFS duration. This can be achieved by inspecting channel state registers of 802.11 cards and signaling such event through the device's shared memory [27], which the LTE protocol stack can periodically inspect. In case of synchronous LBT operation, the 802.11 interface can also be instructed by writing into the shared memory, to immediately generate a CTS-to-self frame that reserves the channel for the desired duration.…”