A Novel WLAN Roaming Decision and Selection Scheme for Mobile Data Offloading

Algorithm 1

Roaming decision and preferable AP selection.

Input: Set the parameters: RSS, RSS_Min, Channel_load, MaximumBSSLoadValue, MinimumBSSRSSValue, ,

Output: AP candidate.

(1) While (1) do

(2) if QoS degrading trigger then

(3) Obtain data from ANDSF server

 (a) Obtain AP candidates Information (SSID, operating channel)

 (b) Obtain Load and RSS thresholds MaximumBSSLoadValue, MinimumBSSRSSValue

(4) qualified_AP_List = nil;

for each  in AP candidate List⁢

 (a) Obtain information of available information from physical Layer,

 (b) Obtain , calculate (3).

 (c) Obtain information.

 (d) if BSSRSSValue &&  < MaximumBSSLoadValue then qualified_AP_List add

If qualified_AP_List is empty then return;

(5) Candidate_AP → APQI = calculate using (4);

for each  in AP candidate qualified_AP_List⁢

calculate using (4)

if  → APQI>Candidate_AP → APQI then Candidate_AP = ;

(6) if Candidate_AP != current AP then

return Candidate_AP;