Mobile Communication Simulation

Demo Description

Our demo program simulates mobile communication service using Xmas as a storage system according to the simplified model for mobile communication service.

The user interface, implemented in Java, shows the movements and call setups of mobile stations. There are four registration areas and 40 mobile stations. The right-below graph shows the number of messages per second processed at the home location register. Here, home location register is the database which maintains the location and service profile information of mobile stations. The right-above graph shows the number of database operations performed at home location register to process these messages.

This simulation compares the performance with/without composite actions. For example, when a mobile station enters a new registration area, the mobile switching center in the area detects its entrance, and then, sends a REGNOT message to the home location register. To process this message, the home location register performs at least three database opearations: one update for the location update of the mobile station and two lookup for authentication and registration cancellation.

If we use only system-provided basic actions, processing this message requires three interprocess communications for three database operations. In contrast, when we define a composite action for processing this message, only one interprocess communication is sufficient. Consequently, using composite actions improve the performance, in this simulation environment, more than 20 %.
 
 

 

The basic network architecture of wireless communication systems consisis of a set of radio ports connected to a fixed wire-line network through mobile switching centers(MSC). User communications take place by establishing call connections through fadio ports, MSC's, and the wire-line network. IS-41, which is one of the major standards of wireless communication, requires user profiles to be stored in a home location register(HLR), which is typically located in a MSC. When a user moves out of the region maintained by his HLR, a copy of the profile is created in a visiting database or visiting location register(VLR) in the user's current region. In addition, the profile in the HLR is updated to reflect the user's current location. Therfore, a MSC usually maintains a HLR and a VLR.

Profile lookups occur when a caller initialize a call to a callee. The caller's MSC searches for the callee's location by first querying the local VLR. If the callee is not currently served by this VLR, then a location request is sent to the callee's HLR. If the callee is not at home, the HLR should query the VLR at the callee's current location for the necessary location/routing information. After finding the callee and establishing the network route, the caller's and the callee's status should be updated. User profile updates also occur when a user moves into a region maintained by a new VLR.