Exploring power saving in 802.11 VoIP wireless links*

Abstract

Batteries are a primary resource in wireless networks for many mobile devices. Minimizing energy consumption without affecting communication activities is crucial to prolong the lifetime and improve the robustness of the wireless connection. One effective way to reduce energy consumption is to set the entire, or part of the system in a low power mode whenever possible. This paper explores a power saving approach for VoIP and presents a new power saving scheme that does not require extra protocol overhead or modifications to operate. Adopting this scheme potentially allows considerable power savings without any adverse effect on VoIP quality. Evidence of this is in simulation results, showing that a device can enter sleep mode for over 75% of the time, with no decrease in throughput.

QoE-based energy conservation for VoIP over WLAN

“…In fact, users QoE is highly degraded when the packet delays are very high, as the number of late packet loss increase. In [10], the authors tried to compute the sleep period for VoWLAN. The authors considered the VoIP packet inter-arrival and the MAC layer delay variation to deduce the duration of the sleep period.…”

“…By considering a simple 802.11 analytical model as well as a VoIP call using 64kbps (typical bit-rate for G.711 calls), they found that the optimal value of the sleep period is equal to 20ms. In [10] and [11], the authors proposed to derive a dynamic sleep strategy to tune the sleep and the packetization intervals dynamically according to the collision probability of the WLAN. By using the collision probability, the author tried to found out a trade-off between maximizing network capacity and energy conservation.…”

“…Both works presented above are difficult to deploy outside one hop WLAN, as they used 802.11 MAC parameters to tune the sleep periods. Moreover, the work in [10] considered only the case of G.711 audio codec, while VoIP applications are usually employing more efficient audio codecs, such as Internet Low Bit Rate (ILBC) [12], G.729a, etc. The work presented in [13], is similar to our proposition in a sense that the authors considered the end-to-end delay and the packet loss rate (both seen at the VoIP level) as the main parameters to derive the sleep period duration.…”

Towards energy efficient VoIP over wireless LANs

“…The authors measure power consumption incurred for tasks like scanning, roaming, receiving beacons and draw inferences for VoIP applications. This work looks at energy from a micro-level perspective focusing only on the one hop network with the AP; similar micro-level work on the topic has been done by the authors of [12,28]. Our work on the other hand looks at energy from a macro-level perspective focusing on end-to-end (multiple hops over the Internet) characteristics of a VoIP session.…”

Practical and Context-Aware Resource Adaptation in Mobile Networks

“…The proliferation of Wi-Fi equipped smart phones promotes the researches that target improving the power saving efficiency of an 802.11 PSM station when it is actively serving Voice over IP (VoIP) sessions [54][55][56][57][58]. In [59][60][61], the authors proposed to utilize proxies to aggregate traffic, thus reducing transmission overhead and energy consumption.…”