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## Location Based Ranking, effects on routing

Using the simple formula for calculating the ranking of users, as follows:

Popularity of user $i = \sum_j \tau_{ij} ( p_j )$
where $\tau_{ij}$ is the time (or number of times) user $i$ has visited the tower $j$$p_j$ is the popularity of tower $j$.

Create a list of towers, with an associated number of times the tower is reported in the dataset, call this the set $p$,

SELECT count(celltower_oid) as count, celltower_oid FROM cellspan GROUP by celltower_oid ORDER BY count DESC

then for each user, get a list of the cell towers, with an associated number of reading for that user, and call this set  $\tau$

SELECT count(celltower_oid) as count, celltower_oid FROM cellspan WHERE person_oid = {USER_ID} GROUP by celltower_oid ORDER BY count DESC

then, for each member of  $\tau$, multiply the number of time the tower is seen in  $\tau$  by the number of time the tower is seen in total from  $p$.

This yields a number for each user, which can be used when initialising nodes in ContactSim (aka LocationSim). I added new properties into the the configuration files, which reflected the ranking of each node, and created new classes in LocationSim, which reflected a new protocol called LBR. When a node is instantiated, is looks up its ranking metric with an oracle class (which reads the data from the configuration file). During the operation of the simulator, when a node get’s an onConnect() event call, it checks it messages to see:

1. if it has any message for the node it is connected to, it passes them on
2. if the node it is connected to has a higher ranking, then it passes all messages on

The initial results show a good delivery ratio compared to PBR

Delivery COST of messages for LBR and PBR using 7 day periodicity, where messaging starts at the first timestep (PBR 7 day Period Start, LBR Start), or after 1 week.

Delivery Ratio of messages for LBR and PBR using 7 day periodicity, where messaging starts at the first timestep (PBR 7 day Period Start, LBR Start), or after 1 week.

This suggest that simply knowing the rank of the users, based on location, significantly improves routing. However, I need to check the algorithm is working before I can say the results are accurate:

• Does the node remove it from it’s buffer when it passes the message on? Yes it does
• Is the node correctly recording deliveries?

Currently working on: Graph of all connected users. Taking a long time……

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