Browsing by Author "Chuang, YM"

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Modeling CDPD channel holding times
(2000-09-01)
Lin, YB
;
Lin, P
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Chuang, YM
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資訊工程學系
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Department of Computer Science
Cellular Digital Packet Data (CDPD) provides wireless data communication services to mobile users by sharing unused RF channels with AMPS on a non-interfering basis. To prevent interference on the voice activities, CDPD makes forced hop bo a channel stream when a voice request is about to use the RF channel occupied hy the channel stream. The number of forced hops is affected by the voice channel selection policy. We propose analytic models tc investigate the CDPD channel holding time for thf the least-idle and random voice channel selection policies. Under Various system parameters and voice channel selection policies, we provide guidelines to reduce the number of forced hops.
Modeling the sleep mode for cellular digital packet data
(1999-03-01)
Lin, YB
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Chuang, YM
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資訊工程學系
;
Department of Computer Science
Cellular digital packet data (CDPD) utilizes sleep mode mechanism to conserve the power of mobile end systems (M-ES's), A timer called T203 determines how quick an M-ES enters the sleep mode, and another timer called T204 determines how often the M-ES wakes up. A large T204 value and a small T203 value can effectively reduce the power consumption at the cost of degrading the frame transmission performance, i.e., more lost frames, longer frame waiting times, and larger waiting variance. When the power consumption budget is determined in a CDPD system design, our study provides guidelines to determine the timer values as well as the buffer size to optimize the frame transmission performance.
Performance of CDPD with timed hop and forced hop
(2001)
Chuang, YM
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Lin, YB
;
Tsai, WN
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資訊工程學系
;
Department of Computer Science
Cellula, Digital Packet Data (CDPD) offers mobile users access to a low-cost, ubiquitous, wireless data network. CDPD can be overlaid on existing AMPS analog cellular systems and share their infrastructure equipment on a non-interfering basis. To prevent interference with the voice activities, CDPD performs forced hop to a channel stream when a voice request is about to use the RF channel occupied by that channel stream. In addition? several timers and system parameters are defined in CDPD to ensure that the normal AMPS activities are not affected by CDPD. This article investigates how the channel selection algorithms, the timers and other parameters affect the performance of AMPS/CDPD systems. Specifically, we study the trade-off between mean CDPD channel holding time and voice incompletion probability. Our study indicates that if AMPS exercises the most-idle channel selection algorithm and CDPD exercises the least-idle channel selection algorithm, then the largest mean CDPD channel holding time is expected. On the other hand, if AMPS exercises the least-idle channel selection algorithm, then the smallest voice incompletion probability is expected.
Trading CDPD availability and voice blocking probability in cellular networks
(1998-03-01)
Chuang, YM
;
Lee, TY
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Lin, YB
;
資訊工程學系
;
Department of Computer Science
Cellular digital packet data offers mobile users access to a low-cost, ubiquitous, wireless data network. CDPD can be overlaid on existing AMPS analog cellular systems and share their infrastructure equipment on a noninterfering basis.Since CDPD utilizes the idle radio resources of AMPS, it is important to ensure that the normal AMPS activities are not affected by CDPD. Several timers and system parameters are defined in CDPD for this purpose. This article investigates how these timers and parameters affect the performance of AMPS/CDPD systems. Our study provides guidelines for the selection of input parameters to aid CDPD network planning. Specifically, we study the trade-off between CDPD availability and voice blocking probability. In this article, CDPD availability is defined as the proportion of time that the RF channels can be used to transmit CDPD data. We observe that selecting too large values for CDPD dwell time and the maximum number of CDPD channel streams will degrade the voice blocking probability without improving CDPD availability. On the other hand, selecting a too large value for the CDPD layoff time will degrade CDPD availability without improving voice blocking probability.