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Network configurations for seamless support of CDMA soft handoffs between cell-clusters

University of British Columbia

Current CDMA networks do not support soft handoffs between adjacent cell-clusters serviced by different mobile switching centers (MSCs). Three novel network configurations are proposed here to overcome this limitation. To allow diversity combining of signals, configurations I and II employ cross links from boundary cells to MSCs serving opposite cell-clusters. On the other hand, configuration in direcdy connects the MSCs of adjacent cell-clusters together to accomplish this objective. A channel assignment scheme associated with configuration I is proposed to reduce the handoff blocking probability by lengthening the handoff transition time. Configuration II expands each cell-cluster by some layers of cells which overlap with adjacent cell-clusters, thus enabling the use of different inter-cluster handoff regions for different handoff directions, an innovation which prevents handoff oscillations which may occur in configuration I while also reducing the necessary number of inter-cluster handoffs. Configuration in accommodates the highest number of calls of the three configurations by allowing the handoff and new calls to fully share the channels linking each cell to the respective MSC. A secondary contribution of this thesis is the development-of a mobility model which enables dimensioning of trunk groups for each configuration. In configurations I and II, the optimal partitioning of trunk groups serving a boundary cell into direct and cross links is determined by mathematical analysis and computer simulation. For configuration IB, the optimal number of trunks required to interconnect adjacent MSCs is investigated by computer simulation. Both vehicle and pedestrian traffic is examined and the performance in all three configurations is compared. Each configuration has its own distinct features: scheme I, configuration I is the simplest; scheme II, configuration I produces the lowest handoff blocking probability by trading off the new call blocking probability; configuration II eliminates the handoff oscillations and reduces the number of inter-cluster handoffs; configuration IE provides the best trunking efficiency to accommodate the highest number of calls.

Thesis/Dissertation

application/pdf

2009-03-07

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http://hdl.handle.net/2429/5714

Electrical and Computer Engineering

University of British Columbia

UBCV

DSpace