Comparing Mobility and Predictability of VoIP and WLAN Traces
Mobility and Predictability of Ultra Mobile Users Jeeyoung Kim and Ahmed Helmy Mobility Models? Mobility models: based on WLAN usage traces
How realistic are these mobility models? How much mobility do these WLAN traces capture? Why VoIP? VoIP Characteristics
Devices are on most of the time Devices are light enough to carry around while in use Ultra mobile? Are VoIP users good enough?
Based on different mobility metrics, we sampled users who are assumed to be ultra mobile (not including VoIP device users) In order to determine the validity of our findings Data Sets
Data Sets (contd) VoIP vs. WLAN : Mobility Prevalence Prevalence for VoIP Device Users Prevalence for General WLAN Users
VoIP vs. WLAN : Mobility Number of APs visited # of APs visited for VoIP Device Users # of APs visited for General WLAN Users VoIP vs. WLAN : Mobility
Activity Range Activity Range for VoIP Device Users Activity Range for General WLAN Users Predictors: Order-k Markov
Assumes location can be predicted from the current context which is the sequence of the k most recent symbols in the location history Markov model represents each state as a context, and transitions represent the possible locations that follow that
context. We use Order 1, 2 and 3 predictors for our prediction Predictors: Lempel-Ziv (LZ) Predicts in the case when the next symbol in the produced sequence is
dependent on only its current state (but does not have to correspond to a string of fixed length) Similar to O(k) Markov but k is a variable allowed to grow to infinity Predictors
Each predictor is run for the WLAN movement trace and for each of the ultra mobile test sets including the VoIP trace set The prediction accuracy is measured as the percentage of correct predictions of the next AP to visit Ultra Mobile vs. WLAN : Predictability
Markov O(1) Prediction Accuracy Using Markov O(1) for 2001-2004 Trace Prediction Accuracy Using Markov O(1) for 2005-2006 Trace Ultra Mobile vs. WLAN : Predictability
Markov O(2) Prediction Accuracy Using Markov O(2) for 2001-2004 Trace Prediction Accuracy Using Markov O(2) for 2005-2006 Trace Ultra Mobile vs. WLAN : Predictability
Markov O(3) Prediction Accuracy Using Markov O(3) for 2001-2004 Trace Prediction Accuracy Using Markov O(3) for 2005-2006 Trace Ultra Mobile vs. WLAN : Predictability
LZ Predictor Change in Trend VoIP Device Users highly predictable What happened? VoIP users becoming more stationary?
General WLAN Users less predictable More and more light-weight devices are being introduced everyday No longer need to have a VoIP device to use the service
Future Work Better predictor for ultra mobile users
60% is better than 25% but it still is not accurate enough Different flavors of Markov Chain, LZ Family, Prediction using regression methods, etc. Better mobility models That will incorporate ultra mobile users better
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