Conference Paper

Queueing model for soft-blocking CDMA systems

Dept. of Electr. & Electron. Eng., Melbourne Univ., Parkville, Vic.
DOI: 10.1109/VETECF.1999.797172 Conference: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th, Volume: 1
Source: IEEE Xplore

ABSTRACT A new model is proposed for the analysis of CDMA systems. This
model is a birth and death process whose birth process considers the new
call arrival rate, the blocking rate, the effect of soft handoff and the
effect of the band allocation strategy in multiband (multicarrier) CDMA
systems. This model accurately predicts the distribution of the number
of calls connected to a base station

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    ABSTRACT: In this paper, a new soft handoff scheme for CDMA cellular systems is proposed and investigated. It is pointed out that some handoff calls unnecessarily occupy multiple channels with little contribution to the performance of handoffs in IS95/CDMA2000-based handoff schemes or systems. To alleviate performance degradation due to channel resource shortage during soft handoff, a new concept of channel convertible set (CCS), which contains several types of handoff calls that unnecessarily occupy extra channels by considering the relative mobility of the calls in the handoff area is introduced. A new scheme that reallocates those extra channels in the CCS to new handoff calls when there is no available free channel in the system is proposed. Furthermore, according to the variation of the CCS, the proposed scheme dynamically adjusts the number of guard channels reserved exclusively for handoff. Then, the feasibility and implementation issues of the proposed scheme are discussed. To evaluate and compare performance indexes of different soft handoff schemes, continuous-time Markov chain models are constructed. Automated generation and solution of the underlying Markov chains are facilitated by stochastic reward net models, which are specified and solved by stochastic Petri net package. Numerical results show that this scheme can significantly decrease both the number of dropped handoff calls and the number of blocked calls without degrading the quality of communication service and the soft handoff process
    IEEE Transactions on Vehicular Technology 09/2006; 55(5):1603 - 1612. · 2.06 Impact Factor


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