Algorithm 3 Sensor Data Feedback

X ← a sensor node in the query window

queryWindow ← the query window

L ← the hierarchical level of X’s PCH in the query window input by the user

Depth ← the depth of the quadtree structure

GetDataOfRegion(queryWindow, L, Depth){

Begin

if (X is a CH)

if (0<Level<Depth-1)

then begin Step1. Collects and aggregates the required sensing data from CMs; Step2. Aggregates the required sensing data by the algorithm in Section 3.4; Step3. Uses PCH selection algorithm to calculate the level = L PCH; Step4. Calculates the routing to the level = L PCH; Step5. Sends the data to higher level PCH by formula (4)&(5) until level = L PCH receives the data packet;

end

if (Level =Depth-1)

then begin Step2. Aggregates the required sensing data by the algorithm in Section 3.4; Step6. Directly send packets to Sink;

end

end

else begin

Step7. X sends the sensing data to its CH

end

end

}