Modeling the static and dynamic guard channel schemes for mobile transactions

There are more and more information services provided on the wireless network. Due to long network delay of wireless link, the transaction will be a long lived transaction. In such a situation, the occurrence of handoff is inevitable, and thus a wireless link held by the mobile unit crossing the cell boundaries might be forced to terminate. It is undesirable that an active transaction is forced to terminate. We propose two guard channel schemes (GCS), static and dynamic, to reduce the probability of forced termination of transactions. In dynamic GCS, the number of reserved channels of a base station is dynamically assigned according to the number of transaction calls which may handoff to this cell while the number of guard channels is fixed in the static GCS. An analytic model based on Markov chain is derived to evaluate the system performance. The correctness of this model is verified by a simulation program. The experimental results show that a significant improvement is achieved by using the dynamic GCS.