Abstract
Optimizing the balance between handoff quality and
power consumption is a great challenge for seamless mobile communications
in wireless networks. Traditional proactive schemes
continuously monitor available access networks and exercise
handoff. Although such schemes achieve good handoff quality,
they consume much power because all interfaces must remain
on all the time. To save power, the reactive schemes use fixed RSS
thresholds to determine when to search for a new available access
network. However, since they do not consider user motion, these
approaches require that all interfaces be turned on even when
a user is stationary, and they tend initiate excessive unnecessary
handoffs. To address this problem, this research presents a
novel motion-aware scheme called network discovery with motion
detection (NDMD) to improve handoff quality and minimize
power consumption. The NDMD first applies a moving average
convergence divergence (MACD) scheme to analyze received
signal strength (RSS) samples of the current active interface.
These results are then used to estimate user's motion. The
proposed NDMD scheme adds very little computing overhead to a
mobile terminal (MT) and can be easily incorporated into existing
schemes. The simulation results in this study showed that NDMD
can quickly track user motion state without a positioning system
and perform network discovery rapidly enough to achieve a much
lower handoff-dropping rate with less power consumption.