Analysis of multiservice hierarchical cellular CDMA networks for intelligent transportation systems

Abstract

We consider two‐tier cellular CDMA networks supporting soft handoff for ITS (Intelligent Transportation System), where mobile users can move in only one of two directions. Both narrowband voice service and broadband services are supported in the considered system. The broadband calls are assigned to the associated macrocell in order to reduce the number of handoffs and the voice calls are assigned to the associated microcell. The handoff calls are prioritized over new calls in the system. To avoid macrocell resource under‐utilization, voice calls in microcells can be allowed to overflow to macorcells. To avoid excessive overflow from the microcells, broadband calls are prioritized over voice calls. Another way to avoid excessive overflow in macrocells is to allow overflowed voice calls to be taken back to microcells. For comparison purposes, we study three models: Model A (no overflow), Model B (overflow without takeback), and Model C (overflow and takeback). Two multi‐dimensional Markov chains are used to describe microcells and macrocells, respectively, and the analytical results for the performance measures of interest are derived, e.g., new call blocking probability, handoff failure probability, forced termination probability, and utilization. Last but not least, simulation programs are written in C to collect simulation results for verifying the analytical results.