HYBRID CONTENTION-ADDRESSING ALGORITHM FOR ENERGY EFFICIENCY IN IEEE 802.11 WAKE-UP BASED RADIO NETWORK UPLINK

Abstract

Power consumption is a key consideration in every Wireless Local Area Network Medium Access Control (WLAN MAC) algorithm design for wireless devices and extending battery life requires more efficient power management scheme considering that carrier sensing by WLAN modules, false wake-ups, collisions and number of contention rounds are major contributors to energy overhead. Researchers over the years have proposed and implemented various schemes using a low power wakeup radio for carrier sense which has proven to be effective. This thesis analyzes the energy efficiency and latency performance of IEEE 802.11 wake-up based radio network uplink using Hybrid Contention-Addressing Algorithm. In this algorithm, Wake-up radio (WuR) senses the channel and wakes its co-located WLAN module when the channel is available for transmission. The station (STA) that wakes up to transmit packet is decided by distributed contention. But the technique put forward in this thesis differs from previous method because each contention round is used to select and queue a set of STAs as against one. The selected and queued STAs then goes on in the addressing stage to transmit as soon as they receive the wake-up message (WuM) in quick succession. The problem of false wakeup stemming from wakeup latency and delay between sleep and wake up of successive STAs is dealt with by the addressing technique which broadcasts an ACK frame modulated with a WuM bearing the unique address of the STA to transmit next. In this way, two stations cannot wakeup simultaneously nor can one wakeup while the other is still in the process of waking. Extensive analysis confirmed that the HCA-CSAM/CA effectively reduces energy overhead by up to 97%, 60hrs increase in battery lifetime and 68.3% reduction in latency compared with ESOC with a better tradeoff between energy consumption and throughput.