Many Wi-Fi adaptors claim to have power-conservation capability. We set out to test just how useful they are.
As a consequence, it would be hard to encourage users to enable PSM in their daily operations. PSM is mostly harmless, but can also have very negative performance impacts. We also noted in the testing of some of the power-save modes on the Intel adaptor that test runs would not complete, timing out with an error message, indicating that the laptop was simply not responding fast enough to meet application demands. Users thus need to be cautioned about setting PSM options without some knowledge of the possible consequences.
Saving energy in any form is a good thing. But, more importantly, anyone who is mobile knows that, after dropping one's mobile computer or communicator on a concrete floor, the most likely failure mode for these devices is a battery going dead. While I still recommend carrying a fully charged spare battery for all critical mobile devices in essence everywhere (understanding that is problematic with laptop batteries that tend to be large, heavy, and expensive), anything we can do to optimise battery life without creating a significant impact on network throughput needs to be considered, if not implemented as a matter of policy. Our tests show, however, that a slam-dunk case for Wi-Fi Power Save Mode cannot be made.
As a final note, it's also important to point out that we've only been considering the client-side elements of power conservation. While infrastructure plays a critical role in the implementation of the protocol-related elements of WLAN power management, it also makes sense to examine the power, and thus the cooling and cost, impacts of all WLAN infrastructure-side equipment, most importantly access points. While not all 802.11n access points, for example, can run on 802.3af power over Ethernet, it is wise to consider access point power consumption when evaluating new equipment. While this may not be the deciding factor in a purchasing decision, it makes sense that such at least be an item in the RFP.
- We put power-saving consumption rates to the test
- Test configuration and procedures
- How power-saving adaptors fared in our test
- Our verdict on power saving Wi-Fi adaptors