 planning of inter-MSC borders. Now we will turn our attention to planning the transport between any given MSC and the other networks and systems with which it communicates. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter MSC Transport Planning It would be a shame to build a code division multiple access (CDMA) network with high capacity and quality on the air interface and then lose the calls on the way to the pub- lic switched telephone network (PSTN), or to another mobile network. We need to do traffic engineering and plan the transport between mobile switching centers (MSCs), as well as the transport from each MSC to the PSTN. We also need to plan transport for data to the public packet data network (PPDN) and private networks. 37.1 MSC-to-MSC Transport Planning Inter-MSC handoffs and some roamer terminations require links between MSCs, and we can reduce costs by carrying mobile-to-mobile calls between MSCs without passing the calls through the PSTN. 37.1.1 Handoffs When a call is handed off from one MSC to another, a connection is formed for that call between the two MSCs. The initial ANSI-41 signaling for the inter-MSC handoff is to establish radio levels and carrier assignments, but much of that signaling is to estab- lish the specific MSC-to-MSC connection that brings the call to its new serving MSC. The packet link for the call is maintained until the call ends or goes back to the origi- MSC.1 1 The ANSI-41 planners did not build soft handoffs into the inter-MSC hand- off specification, but some vendors do allow inter-MSC soft handoffs. Inter-MSC handoffs are handled by packet links over inter-MSC facilities dedicated to handoff traffic. These facilities may themselves be leased from the PSTN, but the handoff links are not set up as calls in the PSTN. MSCs do not hand off calls 