| 摘要 |
A particular method for enabling the service of mobiles by a microcell, in a two tier cellular system, involves identifying a microcell coverage area and offsetting microcell signal strength for a time sufficient to allow a fast moving vehicle, desiring service and having entered the microcell serving area, to exit the microcell coverage area before the call is set up or handed off forcing the controlling macrocell to handle the call setup or handoff. Hence only the mobile radiotelephones of stationary and relatively slow moving vehicles are served by the microcell. There is a substantial offset-coverage overlap period between the locations where a mobile may be found during the offset interval or duration of the apparent reduced signal strength of the microcell and the microcell coverage area. Calls that could be serviced by the microcell are instead serviced by the macrocell because the mobile radiotelephone responds to the strongest signal. This loss in capacity is solved by reducing the offset-coverage overlap. Offset-coverage overlap is reduced by starting the offset or timed duration in response to a broadcast signal sent by the microcell at some predetermined point before the mobile enters the microcell coverage area and by increasing the length of the offset duration or interval by some predetermined increment to prevent service by the microcell to a vehicle exceeding a cutoff speed. Far slow moving vehicles then is a net shift to a reduced offset period within the microcell coverage area and hence proportionately more call setup and handoff requests of slow moving vehicles can be accommodated. Service permissions for call setup with microcells may also be based on certain identification associated with mobile radiotelephones.
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