Tian-Tsair Su

National Chiao Tung University, Hsin-chu-hsien, Taiwan, Taiwan

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Publications (4)1.81 Total impact

  • Source
    Chung-Ju Chang · Po-Chiun Huang · Tian-Tsair Su
    [Show abstract] [Hide abstract] ABSTRACT: We study a channel borrowing scheme applied in a cellular radio (personal communication) system where call queueing and cutoff priority for handoff calls, which can improve the system performance, are also considered. Because the trade-off between the new call blocking probability and the forced termination probability, we heuristically define a cost function, which is a linear combination of the new call blocking probability and the forced termination probability, to find optimal system parameters of the new call queue length, the handoff queue length, and the number of guard channels. The simulation results indicate that the channel borrowing scheme with finite queueing and guard channels can further increase the system capacity
    Full-text · Conference Paper · Jul 1996
  • Source
    Tian-Tsair Su · Po-Chiun Huang · Chung-Ju Chang
    [Show abstract] [Hide abstract] ABSTRACT: For a cellular based PCS system that supports mobile as well as non-mobile users, the forced termination of mobile calls due to handoff failure is an important performance measure, in addition to the new call blockings. Generally speaking, the dropping of ongoing calls annoys users more than the blocking of new calls, thus for systems with small cell sizes some protection schemes should be adopted to reduce the handoff failure probability. However, these schemes do improve the handoff performance but increase the new call blockings on the other hand. This paper proposes a handoff protection scheme that combines the concepts of channel borrowing and cell overlaying. This scheme was originally used in previous work for reducing new call blockings of systems with only one class of non-mobile users and fixed channel assignment. The paper applies the scheme to protect handoffs for the systems that accommodate a mixture of non-mobile and mobile users. By examining system performance measures, it is concluded that the scheme substantially reduces the forced termination probability of mobile calls with almost no impact on new call blocking probability, thus improving the overall system performance
    Full-text · Conference Paper · Dec 1995
  • Source
    Chung-Ju Chang · Yeu-Hsing Yeh · Tian-Tsair Su
    [Show abstract] [Hide abstract] ABSTRACT: In a cellular mobile radio system that supports various types of platforms, a platform may consist of multiple calls. A multiple-call hand-off problem exists as platforms move across a cell boundary. Some recent works have studied the multiple-call hand-off problem. We extend the earlier work by considering the system providing two separate queues for both new and hand-off calls. We analyze the system by means of continuous-time Markov chain approach. The performance measures obtained include the blocking probability of new call, and the terminating probability of hand-off call
    Full-text · Conference Paper · Jul 1994
  • Source
    Chung-Ju Chang · Tian-Tsair Su · Yueh-Yiing Chiang
    [Show abstract] [Hide abstract] ABSTRACT: Queueing of new or handoff calls can minimize blocking probabilities or increase total carried traffic. This paper investigates a new cutoff priority cellular radio system that allows finite queueing of both new and handoff calls. We consider the reneging from the system of queued new calls due to caller impatience and the dropping of queued handoff calls by the system as they move out of a handoff area before being accomplished successfully. We use signal-flow graphs and Mason's formula to obtain the blocking probabilities of new and handoff calls and the average waiting times. Moreover, an optimal cutoff parameter and appropriate queue sizes for new and handoff calls are numerically determined so that a proposed overall blocking probability is minimized
    Full-text · Article · May 1994 · IEEE/ACM Transactions on Networking