Browsing by Author "Fang, YG"

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Billing strategies and performance analysis for PCS networks
(1999-03-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
It is predicted that by the year 2000, U.S, cellular carriers will invest billions of dollars for cellular billing and customer care. Two of the most desirable attributes of the cellular billing systems are the flexibility of upgrade and ability to inform the billing experts quickly about the status of the system to minimize any possible fraud and improve customer service. Although the second attribute can be realized by reporting the billing customer record in real time, this tends to congest the signaling channel, which is not desirable, In this paper, we propose several schemes for the provision of a quick billing status report which maintains low-signaling traffic. The performance of these schemes is derived analytically. We expect that these results may pro,ide a guideline for the future design of on-line billing systems in personal communication ser,ices (PCS's) networks.
Call performance for a PCS network
(1997-10-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
It is well known that, due to the mobility of a portable and limited channel availability, calls of portables may not be completed due to being blocked or terminated during the call initiation or the handover process, The characteristics of the call-completion and call holding times for both a complete call and an incomplete call are of critical importance for establishing the actual billing process in the PCS network. In this paper, we derive the call-completion probability (hence, call-dropping probability) and the effective call-holding time distributions for complete/incomplete calls with a general cell-residence time and a general call-holding time are analyzed, and. general computable formulas are obtained, We show that when fall-holding times are Erlang distributed, easy-to-compute formulas for the probability of a call completion and the expected effective call-holding times for both a complete call and an incomplete call can be derived.
Call performance for a PCS network
(1997-10-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
It is well known that, due to the mobility of a portable and limited channel availability, calls of portables may not be completed due to being blocked or terminated during the call initiation or the handover process, The characteristics of the call-completion and call holding times for both a complete call and an incomplete call are of critical importance for establishing the actual billing process in the PCS network. In this paper, we derive the call-completion probability (hence, call-dropping probability) and the effective call-holding time distributions for complete/incomplete calls with a general cell-residence time and a general call-holding time are analyzed, and. general computable formulas are obtained, We show that when fall-holding times are Erlang distributed, easy-to-compute formulas for the probability of a call completion and the expected effective call-holding times for both a complete call and an incomplete call can be derived.
Channel occupancy times and handoff rate for mobile computing and PCS networks
(1998-06-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
This paper presents a study of channel occupancy times and handoff rate for mobile computing in MC (Mobile Computing) and PCS (Personal Communications Services) networks, using general operational assumptions. It is shown that, for exponentially distributed call holding times, a distribution more appropriate for conventional voice telephony, the channel occupancy times are exponentially distributed if and only if the cell residence times are exponentially distributed. It is further shown that the merged traffic from new calls and handoff calls is Poisson ii and only if the cell residence times are exponentially distributed, too. When cell residence times follow a general distribution, a more appropriate way to model mobile computing sessions, new formulae for channel occupancy time distributions are obtained. Moreover, when the call holding times and the cell residence times have general (nonlattice) distributions, general formulae for computing the handoff rate during a call connection and handoff call arrival rate to a cell are given. Our analysis illustrates why the exponential assumption for call holding time results in the underestimation of handoff rate, which then leads to the actual blocking probabilities being higher than the blocking probabilities for MC/PCS networks designed using the exponential distribution approximation for call holding time. The analytical results presented in this paper can be expected to play a significant role in teletraffic analysis and system design for MC/PCS networks.
Implicit deregistration with forced registration for PCS mobility management
(2001)
Pang, AC
;
Lin, YB
;
Fang, YG
;
資訊工程學系
;
Department of Computer Science
Registration/deregistration with a mobility database called Visitor Location Registers (VLRs) is required in a PCS network when a mobile phone moves between registration areas. Several schemes were proposed to deregister a mobile phone after it moves out of a registration area. A simple scheme, called implicit deregistration, is studied in this paper, which does not specifically deregister any obsolete record in the VLR. If the VLR is full when a mobile phone arrives, a record in the VLR is deleted and the reclaimed storage is reassigned to the incoming mobile phone. It is possible that a valid record will be deleted. If so, the VLR record of a mobile phone may be deleted before a call to the mobile phone arrives. Our previous work assumed that the incoming call setup would be lost. In this paper, we propose forced registration to restore the VLR record before the call setup operation can proceed. With this modification, implicit deregistration totally eliminates the deregistration traffic at the cost of creating some forced registration traffic. We derive the record-missing probability and the portion of the network traffic saved by implicit deregistration. Our study indicates that implicit deregistration with forced registration may significantly reduce the deregistration traffic if the user mobility is high and the number of mobile phones in a registration area is not very large.
Mobility management and signaling traffic analysis for multi-tier wireless mobile networks
(2005-09-01)
Fang, YG
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
A multi-tier wireless system integrates the high-tier wireless systems and the low-tier wireless systems into a single system to provide the advantages of both tiers. Such a system is expected to provide better service (more service availability and more cost effectiveness to the users) at the expense of the extra tier-switching management. Examples of multi-tier systems include the interconnection network of a satellite communication network and a terrestrial cellular network, the integration of low-power systems such as wireless personal area networks and cellular systems, and the integration of higher mobility of cellular systems with low-mobility wireless local area networks. In such a system, mobility management is critical, because only when the location of a mobile user is known or tracked can the service quality for the user be guaranteed. In this paper, we study a few mobility management schemes for multi-tier wireless mobile networks under more realistic assumptions. Performance evaluation in terms of registration signaling traffic is carried out, and easy-to-use analytical results are obtained. It is also clear that for service availability, the two-tier system is better than the single one-tier system; we therefore study the probability that a call is forced to terminate in the single low-tier system because the low tier becomes unavailable during the call (such a call can be continued in the two-tier system).
Modeling PCS networks under general call holding time and cell residence time distributions
(1997-12-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
In a personal communication service (PCS) network, the call completion probability and the effective call holding times for both complete and incomplete calls are central parameters in the network cost/performance evaluation, These quantities will depend on the distributions of call holding times and cell residence times, The classical assumptions made in the past that call holding times and cell residence times are exponentially distributed are not appropriate for the emerging PCS networks, This paper presents some systematic results on the probability of call completion and the effective call holding time distributions for complete and incomplete calls with general cell residence times and call holding times distributed with various distributions such as Gamma, Erlang, hyperexponential, hyper-Erlaug, and other staged distributions, These results provide a set of alternatives for PCS network modeling, which can be chosen to accommodate the measured data from PCS field trials, The application of these results in billing rate planning is also discussed.
Portable movement modeling for PCS networks
(2000-07-01)
Fang, YG
;
Chlamtac, I
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a nem model for the portable movement in personal communications services (PCSs) networks. Based on this model with general interservice time and registration area residence time distributions, analytic expression for the probability that a portable mores across K registration areas (RAs) is obtained. Busy-line effect on this quantity is also studied and analytic expression is presented, The result given in this paper is very useful for the cost analysis for location updating and paging.
TTL prediction schemes and the effects of inter-update time distribution on wireless data access
(2004-09-01)
Fang, YG
;
Haas, ZJ
;
Liang, B
;
Lin, YB
;
資訊工程學系
Modern mobile networks, such as GPRS and UMTS, support wireless data applications. One successful example is the ever popular i-Mode in Japan. Wireless data services ( wireless Internet) become more important as more and more customers of handheld devices enjoy the convenience of the ubiquitous computing. To improve the effective wireless data access, the time-to-live (TTL) management for data entries becomes important due to its use in effective caching design. In this paper, we study three TTL prediction schemes and investigate the effects of the inter-update time distribution on the wireless data access. Performance analysis is carried out via simulations as well as analytical modeling. We expect our results will be useful for the future wireless data access systems, in which transmission power for mobile devices is more limited.