ASN – Access Service Network.
  • Establish layer 2 connections between the BS and the MS. 
  • Transmit AAA messages to the home NSP of the MS. 
  • Assist the high level to establish layer 3 connections with the MS and assign
    the IP addresses. 
  • Perform the radio resource management (RRM). 
  • Perform the intra-ASN mobility management and handover. 
  • Perform the intra-ASN paging and location management. 
  • Establish and manage the tunnels between the ASN and the CSN. 
  • Store the list of temporary subscriber information, which is similar to the function of VLR in a 3G network.